Mega Tsunamis caused by meteors:

Mega Tsunami: cause by island shelf, mountain side collapse

Gamma ray burst: a near miss might not be an extinction event

Coronal mass ejection: -massive communication and IT failure

Weakening magnetic field: -atmosphere gets ripped away faster

Mega Volcanoes like Yellowstone an extinction or near extinction event

Non-visible nebulae like patch of space containing matter or radiation with adverse(?) effects.

These seem more like Mega events rather than Colonization events. I do however like most of them, when, and its a big when, I get around to the Mega Events I'll be sure to use these.

house like trees.

this planet is filled with large trees that form nearly perfect residences for our citizens.

the catch is that the plants grow to maturity die and rot away in a mere 5 years and are only viable living habitats for 3 years.

B- encourage a minimalistic lifestyle among the people to make moving easier as it will happen every few years.

Maintenence -100% 

P- allow those that wish to live in their tree houses to do so but also set aside land for those who wish a more permanent lifestyle.

approval + 20 % 

M- you say these trees grow to the size of a house in just a year.... i feel we should invest in the furnace market

manufacturing +20% 

Not Quite There Yet.

Pre-spaceflight civilization already resides on this planet. They've industrialized, but still haven't even made it to orbit yet.

• B:  Let's introduce them to the wonders of interstellar travel. See the sights! Oh, and ask them nicely where we can put some of our stuff so we don't step on each other's toes.  +20 B, +15% Tourist income for the planet, Lose one planetary tile
• P:  I'm sure we've got lots of trinkets they will think are wonderful. Let's sell them to the natives in exchange for land. LOTS of land. In prime locations. +10 P, +15% planetary economy, -25% planetary Influence
• M:  For a pre-spaceflight society, they seem pretty darned handy with those wrenches. Put them to work in our spacefleet fixing stuff. You know, like toilets. +10 M, -15% to maintenance of all ships built at a sponsored shipyard, -20% to planetary morale.

Lava Galore!

This planet experiences very frequent lava flows, covering vast areas of land. On the good side, lots of neat minerals are right near the surface; unfortunately, these eruptions aren't from the same places, so people need to keep moving around to avoid being covered in hot rock.

• B: Safety of our settlers is paramount! Build the settlements on tall platforms to protect them from the flows. And see what interesting tidbits we can learn from such a unstable planet.   +10 B, +25% maintenance to all buildings, +25% planetary research
• P:  We can't have our settlers getting cremated on a regular basis. That kills productivity. Not to mention morale. Set them up with mobile living facilities, which we can move next to the most advantageous mineral deposits.   +10 P, +10% planetary economy, -10% manufacturing
• M: Minerals! Lots of them! Great!  Get the colonists to start mining right away. "Volunteer" anyone who complains about the heat to the planetary geology division, responsible for testing the newest lava flows for mineral content. Sorry they're a little light on heat shielding this quarter.  +10 M, +10% Manufacturing, -50% population growth

Flight of the Bumblebees

Large swarms of insects periodically sweep across the planet. They don't seem to eat anything while doing so, but it freaks a lot of the settlers out since the swarms can actually block sunlight for awhile.

• B:  Keep the more sensitive members of our colony indoors during these periodic swarmings. In the mean time, let's study how those swarms move and migrate - perhaps we'll learn something useful about how they manage to migrate so far with no apparent guidance.  +10 B, +5% Research, -10% manufacturing
• P: Set up repulsor fields around the settler's houses, to keep the bugs from bothering them. Suggest that the more squeamish colonists need to "get over themselves, they're just bugs". And look into where all those bugs go when the swarm ends; something tells me there's a rich source of food for our livestock there.   +10 P, +10% Economy, -5% approval
• M: Yuk. I hate bugs. Especially big swarms of them. Bring in lots of electric arc lamps to zap them. Grind up the dead bugs and feed the colonists with it; no use in wasting good protein!  +10 M, +10% food, -25% tourist income

I think you are the right track.

Just a thought ...have 3 version for every event? One being a plus another a negative and one that add something but takes something else away...

I do not have an internet connection and I have to borrow one I will write more when I can.

I have an idea I think you will like but I am out of time right now.

Rapid tectonic drift

Frequent earthquakes plague the entire planet, continents form and break up in a blink of an eye (speaking of course on a geological time scale). This stressed environment has given rise to an evolution of a biodiversity that has taken fantastic and extreme forms.

B: Do nothing about the drift. Who are we determine the right way for evolution to go? The frequent earthquakes will force increase building maintenance, but the fantastic flora and fauna will draw in the tourists. Maintenance cost +50%, tourism +100%

P: Stabilize the most violente plate collisions. Mitigation is the way to go. Maintenance cost +25%

M: Use nukes to welt the plates into fixed positions. Who cares that some frigging plants and creepy ground crawlers might die off? The ones that don't fry in the initial fusing process can be used as food stuff. Food +100%, influence -25%, approval -25%

OK prepare to be underwhelmed:

Flavor test:

"Our scientists are not sure why but maybe an [insert Precursor artifact that you want] didn't crystallize into large central crystal that would be easy to find and mine but form picoscopic particles/waves that the planetary gravity well scoops up and accumulates on the planet and gives the following [bonus]."

Like the idea erischild. Doesnt fit with fire rainbows though, I will however fit it in elsewhere!

Pics of Fire Rainbows:

Dude, you're doing everything I wanted to do but didn't have time. Good on you. You're doing God's work.

Event: Such and such world is experiencing a strong resurgence in radical religious zealotry - they claim to be an offshoot of the Wormhole-alien religion of the Prophets known as the "Pah Wraiths." Their leader claims that is it time to pursue a crusade against the godless aliens of other worlds and is encouraging his followers to take up arms. What action should we take?

B: People yearn from something to believe. Through education and outreach this surge of faith can be channeled into something beneficial for our entire society. (+10% approval, -500 bc)

P: People's beliefs are no concern of the state. Stillinall, I've found that the best way to stymie a religious nut is to tax his order. Church and state, after all. (-10% approval, +5% tax revenue)

M: A crusade? Now that's the kind of belief system I can make work for me! Conscript the lot of them, I knew a few godless infidels that deserve the business end of the god's hammer. (-5% approval, +25% soldiering bonus)

Emphatic Planet

This planet seem to have a semi kind of sentience and fosters feelings of empathy in the colonists. Our landing scientists believe that over time the planet might develop a harmonious bond with the people whom dwell within its sphere of influence.

B: Cool, lets use this and spread harmony across the universe and with diplomacy quell all wars. Resistance +25%, diplomacy +20%, influence +20%, 1 Benevolence Point per 10 turns.

P: We should be careful, for as much as we are influenced by this bond so seems the planet to be influenced by us. We should not spread this bond to other planets (for now). Resistance +25%,  happiness +20%, growth +20%, 1 Pragmatic Point per 10 turns.

M: Empathy, bah humbug. It is just a small step to go from love to hate. Lets teach this planet to hate our enemies. The fact that it will drive our populus slightly mad will make them easier to convince to join the military. Resistance +25%, Happiness -20%, Growth +20%, 2 Malevolence Point per 10 turns.

Free floating planetary core

This planet has an off-centre free floating core, which make the planetary spin irregular. The local biosphere suffers no ill consequences since it evolved in this environment. However while our colonists can adapt to a different day length, a fluctuating day length is a different thing all together. Settling here will present us will unique problems. Not only mental fatigue which will diminish production, but the sleep disruption will also massively impact any intellectual pursuits. 

B: Facilitate the mental well being of our people and take the hit in the productivity. Raw Production -20%, Research -20%

P: Let try to work the best we can and use only non-harmful drugs to mitigate the worst of the problems. Happiness -10%, Raw Production -10%, Research -10%

M: Pump the workers full of drugs. They are supposed to work, not lollygagging around. Work them till they drop. Happiness -20%, Research -20%

Tectonic shift increasing causing 50% less food production and subsequent population decline.

Trying to lie with a straight face: "The force(ful) in this case is the extra Benevolence/Pragmatic/Malevolence Point(s) the choices give." 

However the awful truth is, it was just a stupid spelling mistake. But hey, English is my fourth language and my linguistic skills are average at best, for i am more a beta and a science oriented kind of guy. You people are lucky enough that any text i post here is at least half readable and not filled with all kind of technical jargon and kiwiisms. So there, a valid excuse.

But seriously Publius of NV, nit pick away. When i make a mistake, and someone points it out (in a civil and constructive manner), i will view this as an addition or correction to my knowledge.  The amount of knowledge that i do not know far surpasses the amount of knowledge that i have, and what i think i know is not even close to 100% reliable.

Only the arrogant believe they don't make mistakes, only fools don't listen to other people, and only total blithering idiots don't change or adapt when their flaws or mistakes become apparent. I try to be none of these, but on occasion will fail miserably.

@ androshalforc - Are you the same guy from CivFanatics?