Tori Amos has invited amatures to create a music video for her song Bouncing off Clouds. Details for the contest are available here.
They provide multiple camera angles of Amos performing against a green screen back ground. It appears as if there are essentially no other rules. Entries have to be in by the 24th.
The files are 900MB
each, so keep that in mind if you decide to download them.
It appears as if the producers of the raw footage expect contestants to use motion tracking software, since they taped tracking marks to the green screen. That's a challenge...
Studio Artist has some tools for keying out colors under the Canvas menu item. I think that first you would have to run a color simplify operation on the footage to make the green back ground more uniform.
Anyway, even if you don't do anything with the footage, you get a free copy of a pretty good Tori Amos songe out of the deal. Also, there's a neat little Final Cut tutorial on that page.