The Collaborative International Dictionary of English v.0.48:

Curio \Cu"ri*o\ (k?"r?-?), n.; pl. Curios (-?z). [Abbreviation
   of curiosity.]
   Any curiosity[3] or article of virtu; any object esteemed for
   its unusual nature.
   [1913 Webster +PJC]

         The busy world, which does not hunt poets as collectors
         hunt for curios.                         --F. Harrison.
   [1913 Webster]

WordNet (r) 3.0 (2006):

curio
    n 1: something unusual -- perhaps worthy of collecting [syn:
         curio, curiosity, oddity, oddment, peculiarity,
         rarity]

Moby Thesaurus II by Grady Ward, 1.0:

72 Moby Thesaurus words for "curio":
   a continental, a curse, a damn, a darn, a hoot, abnormality,
   anomaly, bagatelle, bauble, bean, bibelot, bit, brass farthing,
   button, cent, conversation piece, curiosity, exception, farce,
   farthing, feather, fig, fleabite, folderol, fribble, frippery,
   gaud, gewgaw, gimcrack, hair, halfpenny, hill of beans,
   improbability, jest, joke, kickshaw, knickknack, knickknackery,
   minikin, mockery, molehill, museum piece, nonesuch, oddity,
   peppercorn, picayune, pin, pinch of snuff, pinprick, pretty-pretty,
   prodigiosity, prodigy, rap, rarity, red cent, row of pins, rush,
   shit, snap, sneeshing, sou, strange thing, straw, toy, trifle,
   trinket, triviality, tuppence, two cents, twopence, whatnot,
   whim-wham