At Blockbuster, if you trade in any PS3 game, you get a free blueray movie rental. This is worth £4.50. If you are taking advantage of some of the prices they are giving (buying a game for £14.99 and trading in for £20-30 for instance) then its a little added bonus on top.
I traded in Ninja Gaiden Sigma and got £28 for it, it only cost me £29.99 - so i effectively got more than i paid for it.
I know its not the worlds best bargain, but if your trading games in anyway, its worthwhile for some peeps to know about.
Be gentle :P