LittleBigPlanet is definitely, definitely recommended. It's pretty much amazing.
If you like fighting games, there are a bunch of great ones on the system. Bunch of us have Soulcalibur IV (got quite a bit of immodesty in it, buyer beware). I'm a bit of a fighting game enthusiast, and could rave for hours about a bunch of 'em.
If that's not your cup of tea, a lot of us also have Burnout Paradise. It's a lot of fun. A lot of fun online, too. No same-system multiplayer (you can buy a $10 upgrade that gives you "hotseat" same-system multiplayer), though. Still, it's pretty cheap and fun.
It hasn't quite caught on around here yet, but if you're looking for a shooter, I highly recommend MAG. I'm not in the business of recommending shooters, so that's a big deal. First-rate competition and mechanics. It's all teamwork-driven, too. If, like me, you're not the best hunter in the world, you can still be a very important part of the team by keeping others up and running as a medic or engineer. Not to toot my own horn, but I
recently reviewed it if you want more intel.
Once I know more about your preferences, I can come up with better recommendations.
Also, saw and accepted your friend request. Also, welcome to the PS3 brotherhood... er... chapter.