Oh, and some, not so. Yikes.

Trying to complete the developer levels before I start doing any community stuff.  If this post is still active at that time I'll post whatever I run across.   
 
PSN: dirtydata 
XBL: dirtydata 

I've only played a few good ones, but they were really really good considering the game had only been out 2 days. 
 
Try  
Blast Radius, Author:Johnee.  ( Custom menu, custom voice, options) 
and by far the best... Omicron! Its a top down rpg style game, with amazing visuals. 
I also liked Gnome Cave.

" I've seen all the trailers and there seem to be some amazing levels from the beta. I did some searching last night and the only LBP2 specific levels I found were horrible!  Do any of you have any favorites, either from the beta or otherwise? "

 http://lbp.me/v/w-26h5 
 
Galactic Base Defense, solid tower defense game. Set up a laser in front of the spawn point in stage 3 ;)

Here are some levels I really enjoyed (some are probably going to mirror other posters' favorites.) 
  

• Galactic Base Defense 1.2 
• Omicron Neon City
• Mediterranean Street Racing
• Top Down Zombies V1.1
• Blast Radius (it cannot be said enough how amazing this is. Seriously.)
• Super Sackboy Bros 3D
• Duck Blaster 

Blast Radius has gotta be the best thing out right now (that I've seen at least).  Added a bunch of levels to my queue but they all ended up sucking.  There was a Street Fighter game that was somewhat creative but just not very fun to play.
 
I'm noticing, now, after playing through a lot of the singleplayer that there are a lot of community levels that are just bad copies of Media Molecule levels.  Hopefully the really good creators will release some more stuff.
 
Someone needs to make a Zelda game; top down style!  Seems easily feasible considering what I've seen out there already and MM levels.  Or you know...I guess they could do something original as well..bleh.

Continuing the trend of stickied threads with typos in the title! I just finished the story campaign so I'll try some of these levels out.

http://lbp.me/v/qb38m7

http://lbp.me/v/p914y

http://lbp.me/v/r8rc0e

I enjoyed the gnome cave, but really, I think you'll need to give it a week or two for the first wave of truly great levels to be released.

Hyperball , shocked no one mentioned it, that game is so good it could (and should) be a PSN/XBLA title. HYperball check it

"  http://lbp.me/v/wt45z3
 
http://lbp.me/v/wszdcm 
 
 http://lbp.me/v/ww3fgz   I love these levels. They're wonderful. "

You can't go wrong with any of the MM Picks.

  http://lbp.me/v/x-cvm9
 
Unique art style, unlocks a hard mode for the level when you beat it once.

This is a pretty rad Ghostbusters level.  
 
http://lbp.me/v/px1mjz

This is the first level of a full game created in LBP2.  The Playstation Blog has been promoting it the past week or two.
 
Hansel & Gretelbot
 
I haven't played it yet, so I don't know if it's actually good.

 http://lbp.me/v/ycvd4x

I just finished making a level. and I think it's pretty good. It's inspired by VVVVVV and I put a lot of time into it. Enjoy!
MMMMMM

 http://lbp.me/v/z-3b86
 
It's by far the best Star Wars level I've seen. One of my favorite levels, period.

Yes, his levels are great.

This has got to be one of the best levels I have ever played, just finished by my friend nightshade94123. 
 
http://lbp.me/v/1fg1ck