T.O.M.E. also. I've been playing Tales of Maj'Eyal and Zangband on my Linux rig off and on for years now. Haven't beat either, but I still have fun playing them.
I enjoyed playing Zangband due to the large amount of races you can choose and the fun combos you can make (Kobold Death Knight just for the hell of it). ADOM was fun the other way, as it had a lot of character classes compared to the available races, and the random mutations also add to the craziness. T.O.M.E. rewards multiple play throughs by making more classes and races available as you unlock achievements. T.O.M.E., ADOM, and Zangband all have linux installation files. What is the best rogue-like out right now for varied character builds regardless of gaming platform?