
First, I think it is my traditional job to point out that any collaborations or experimental single projects are a great fit for the ludumdare.com competitions (sometimes even the monthly Mini LD ones)... I would totally be up for a cooperative game. The IRC channel #gosu on freenode also usually has a few people tinkering on games during bigger competitions.
Then, wow, archery! I would have needed those for my last game. How about animals? :D I have a rather experimental board game based on various animals going...and have no idea what to do about sound effects. It's not Gosu due to platform constraints, but I plan to port it depending on its reception.