Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "trendy":
   a la mode, all the rage, all the thing, coxcomb, current,
   exhibitionist, fashionable, flash, grandstander, groovy, hip, hot,
   in, in fashion, in style, in vogue, mod, modern, modish, new,
   newfashioned, now, popular, prevalent, show-off, smart, stylish,
   swank, swish, tony, ultramodern, up-to-date, up-to-datish,
   up-to-the-minute, voguish, with it, with-it