UnNethack is really good. Like the sibling poster, I too play a lot of Qud, but it kind of comes from a different tradition of roguelikes so it might not scratch the same itch. It's spectacular, though.

Cogmind comes to mind as being a neat riff off of the "hack" style of roguelikes, and the developer is super open and cool about the game. Or, for a little bit of an older but a much broader experience, you could check out Dungeons of Dredmor.

(As you mentioned--Jupiter Hell just came out and it's the sequel to DoomRL and it's awesome, if you like more coffeebreak-style roguelikes!)