I think people who really get stuck into Arc should be called ArcTicks.
But seriously: I read "arcist" with a "ss" sound instead of a "k" sound for the "c", and it sounded rude. Mind you, that's with an Australian accent.
Rummaging through /usr/share/dict/words: the Arc Forum can be the Arcade, and its regular posters Arcadians, with perhaps the top poster (in quality, not quantity) given the title Archimedes; backwards compatibility issues are archaisms; PG is the Archangel, or perhaps the Architect (Lisp is the red pill!); Arc programmers in general are Archaeologists; the growing collection of Arc websites form the Archipelago; type safety is discussed in a forum called the Archetype; old posts go into the Archive... The potential is endless!
Unfortunately, "cracker" already has the meaning of "one who breaks into other people's computer systems or software." We've had to fight hard enough to retain the real, positive meaning of "hacker" (and haven't entirely succeeded); "cracker" is a lost cause.