well, i'm with the others, a project like our album projects sounds like a good idea to me, that way you can get the experience of many of the different members of the community on the project, not just one...
Just one thing tho, and thats styles that people can do... it depends what you want to see for certain themes, for example, i'm good at upbeat synth driven music, others are better at rock and some at orchestral.
If people take there pick, then that persons arrangement style might not suit the theme... Its not a big problem at all however.
I'd post the tracklist and give us an idea for you want for each theme so mixers may pick a track thats better for their prefered style. That is if you go down the different person per track route.
Btw i'm interested as well