hobbyist

from WordNet (r) 3.0 (2006)

hobbyist
    n 1: a person who pursues an activity in their spare time for
         pleasure

from Moby Thesaurus II by Grady Ward, 1.0

20 Moby Thesaurus words for "hobbyist":
      addict, bug, collector, demon, eager beaver, energumen, enthusiast,
      faddist, fanatic, fiend, freak, great one for, hound, infatuate,
      nut, pursuer, rhapsodist, sucker for, visionary, zealot