Brogue is an ASCII art styled Rogue-like game by Brian Walker. It is a direct descendant of Rogue, unlike other popular modern rogue-likes, and it favors simplicity over complexity, while trying to ensure that the interactions between components will be interesting and varied.
Cataclysm Dark Days Ahead is a classic styled ASCII roguelike game for PC, Linux and Mac.
ADOM is a classic roguelike, deep, detailed and difficult. It has both ASCII and fully graphical modes available (you can switch on the fly at any time).