Guys!!!! How about we help out the impulse shopper here with some cheap, yet amazing titles no? :P I recommend getting a PSN account ASAP and picking up some of the following!
SUPER STARDUST HD, NO JOKE, JUST BUY, THANK ME LATER...
Warhawk!!!! (multi-player)
Wipeout HD (multi-player)
Pixel Junk Monsters (awesome tower defense game ^^)
Pixel Junk Eden! (you gotta play to understand man :D Totally awesome)
Everyday shooters pretty awesome :)
Ratchet and Clank Futures! TOD
Uncharted
Resistance Fall of Man, (to make you want the second one even more, which has amazing multi-player :D)
From 0 to KICKASS in .stupid seconds.