If you could work for any developer...

[Not That]

Valve, as an AI designer, because Valve's always been huge on AI, and their games are freaking awesome.

If not them, then Ubisoft Montreal on either the Assassins Creed or Prince of Persia teams, because both of those franchises are great fun, if for no other reason than just because running and jumping makes the little chimp inside me happy.

 

[Marter]

Probably UbiSoft Montreal. I like their games, and it would be fun to work with them. I could also improve my French. ^_^

 

[masher]

Blizzard or Valve

This is exactly what I was going to say. Ninja!

OT: The reason is that both of these companies not only make great games, they keep the games up to date and have a sense of humor about themselves which is refreshing.

But I guess I'd say Rockstar or Doublefine would be cool too.

Agreed! They know how to have fun and how to connect with their customers. Blizzard's high quality Cinematics are also a plus for me. Those never cease to amaze me.

 

[Seth Smith]

I'd want to start my own, myself. Love being my own boss. Have to have good business sense, though.

 

[Dan Steele]

Its my life goal is to work for Insomniac games, i love there games, i have special contacts with there developers (I hold many conversations with them, they helped me become a 3D animator.) And the work days there, just let me tell you how fun it was when i got the opportunity to work for them for a week(One of the employees Bryan Intihar, let me try it out as a result of making a 3D Detication to Insomniac.)It went something like this:

Let me tell you a little bit what i experianced
Nerf wars Monday
Frag-Fest Friday
A massive kitchen
and a great happy enviroment.

There not always like this however, when they are working on there big game titles like the Resistance franchice, Its practicaly like the CEO Ted Price gave the order "Battle Stations", These gentlemen and ladies are deticated to game design.

 

[fingerbang143]

Bethesda because they are clearly smart people with a huge amount of talent. Or double fine becuase their hilarious.

 

[TheHecatomb]

Epic Games, because I'd actually fit in their ZBrush-orientated pipeline and I totally love pushing the boundaries of UEngine 3.

 

[repeating integers]

Bungie, because then I'd get to be one of the people in control of the world when their plan is complete.

Or maybe Bioware.

 

[demoman_chaos]

Taleworlds, the makers of the Mount&Blade series. That combat engine has so much potential for epicness just waiting to be unleashed.
Add in a Total War graphics engine sort of deal to increase the scale of the battles without raping your computer and better troop commanding (Total war style so you can draw up your lines as you want them) to make M&B godlier than it already is.
Then make a spin-off Oblivion-esque free roam RPG where you command just a small 8 man team (having 40 people follow you would be tough, be too much like those old Verizon commercials) and roam around doing quests and stuff like that. Magic and all that could be added as well. The M&B combat engine would make it far better than Oblivion's swordplay, especially when you don't have a shield. It would also make horses useful, Oblivion horses are pointless when you can run faster then them on foot.