Although I haven't reviewed the footage yet, this seems like an interesting excercise for editing:

http://www.stockstock.org/

Stockstock is a film festival consisting of short films made entirely from stock footage. We select a limited amount of stock footage and give it to you; your job is to make it into some kind of short video presentation.
<font size="2" face="Verdana, Helvetica, sans-serif">Footage is from Prelinger archives, so it could be a 'challenge'.