What are some of your favorite custom maps? I've pretty much only been playing league matches and practice matches so far, so I thought it'd be fun to check out some cool custom maps. I'm looking for what are known as "Use Map Settings" maps, not custom maps to just play the standard game on. 
 
I've heard some good things about Nexus Wars and Evolves, I guess those will be some of the first ones I try.

Until a real DotA is out, I will have to stick with Nexus and Chess as the backup for boredom.

None of the custom maps out now are interesting. They got really creative in the first SC but I haven't seen any of that yet.

Nexus Wars as already mentioned is a great game.
BattleCraft is similar, but faster paced (Sometimes the game ends in less than a minute if the opponents are not paying attention) and does not involve structures as much.
 
A Standard Tower Defense is very similar to the Element TD of WCIII:TFT for those who played that.  For those who didn't its a standard TD with no mazing but lots of tower types and upgrades.
 
Blood Pressure Marathon is one of my personal favorites.  Its a race game where you spawn as a different unit each leg of the race.  The goal is to complete 11 laps of the map.  Each lap is 4 legs long.  The units can attack each other and use some of their special abilities (The mothership gets vortex, Battlecrusier gets Yamato Cannon, etc).   The victor is nearly totally random because sometimes you will spawn as a Viking or Phoenix and some times an Overlord or Infested Terran.   There are all kinds of hilarious ways to slow down your competitors.  You can spawn an infestor under your control to Fungal growth your enemies, or outright  kill everyone on the leading lap, or trap all the non-flying units by calling down tons of MULEs.  Those abilities and the ability to force a respawn on yourself are limited by resources which everyone starts with a small amount of and cannot be earned.  Some of the units can harass others as well.  Infestors obviously have Fungal Growth and Infested Terrans to spawn, the Raven can drop murderous turrets, the SCV and Probe can build Command Centers and Nexuses (for free!) to block the path, or OVerseers can build walls of invulnerable changlings.  Sadly, there are a few bugs in this game (getting stuck as a snowglobe, the spine crawler can't uproot, ITs and Changelings can't be killed ever) which make it less fun, but with enough players you will certainly be killed quickly or finish your leg of the map and can get to be something else.  I would say 5+ players is ideal, any less and the game feels boring. 

Have any good custom maps come out since the game's official release? I didn't play in the beta so I don't know much about what's been done already.

" Have any good custom maps come out since the game's official release? I didn't play in the beta so I don't know much about what's been done already. "

I've played some Circle TD, a neat concept and good for scratching the ol' tower D itch.