Maybe instead of tangible rewards, why not access to special areas? Let's say there is a secret forum that could be implemented or extra armatars, or a large point increase. There are several ways to make prizes that wouldn't cost the site anything.
The same people wouldn't keep getting them cause they would have to cash in Armor Points to get them or they could limit it at one per person and if not then they should at least put them in the store for real currency or as Asherlee mentioned they could always go with the intangibles I think Armor Games needs a newsletter where they tell us what they're working on and or planning to do :P
