how about these crocodile clips to create instant grommets on whatever material used for Chroma Keying and bungee cords. This idea may have already been tried or discussed on here but I actually saw these at Home Depot (section where the tarps are kept) for much less that this camping site sells them for.
http://www.campingworld.com/browse/skus/index.cfm?deptID=2&subOf=48,10&skunum=20666&affiliateID=1126
edit: sorry, I meant to post this in general discussions

I already have some of those and it never occurred to me to use them for green screens or reflector fabric. Thanks for the tip!