I am a big fan of NetHack for quite some time now and today I discovered the wonderful world of other Roguelike games.
The first game I tried was ADOM which has an overworld, unlike NetHack.
Then I found the 7DRL-Contest via Wikipedia, really great stuff.
Check out CastlevaniaRL and DiabloRL.
Here is some more stuff for you to read, I have to take a look at DoomRL now. :)
(via: Rogelike fun)