Cat and the Hack Angband is an entertaining variant. It contains new races, modified combat, and allows slays and brands to be gained when using items other than weapons.
"Neko" started work on CatHAngband 1997, updated it to Angband 2.9.1 code in 2000. In 2003, Evan Jenkins announced his intention to port it to a more modern codebase, which was completed and released in September 2003. There has been no activity since.