Have you considered joining or gathering your own team of developers and collaborating on a game with a few other developers? I think if you share enough of the vision it could be very rewarding and would help you to keep motivated. Of course it all depends on who you team up with and you might not have success in your first shot but there are some other decent developers out there with some great ideas and talent.

Kev: Considered yeah, but finding a team that isn't either

a) Almost 100% done with what they thought out originally and don't have anywhere else to go
b) Willing to push and pull ideas rather than sticking to one fixed vision
c) Low on experience and thinking that you can build the biggest game in the world because there are more than 1 of you.

seems to be pretty difficult. I've mentioned before I don't play well with others often so it might not be motivating for other people on the team either.

Has anyone got a good idea and the motivation to lead a team? I can happily contribute time, ideas and code but without a leader, an artist and a designer it'll all end in tears :(