WordNet (r) 3.0 (2006):

front man
    n 1: a person used as a cover for some questionable activity
         [syn: front man, front, figurehead, nominal head,
         straw man, strawman]

Moby Thesaurus II by Grady Ward, 1.0:

71 Moby Thesaurus words for "front man":
   Charlie McCarthy, agent, anteriority, bold front, brave face,
   brave front, connection, creature, deputy, display, dummy, facade,
   face, facet, facia, figurehead, fore, forefront, foreground,
   forehand, foreland, forepart, forequarter, foreside, foreword,
   front, front elevation, front matter, front page, front view,
   frontage, frontal, frontier, frontispiece, go-between, head,
   heading, interagent, interceder, intercessor, intermediary,
   intermediate, intermediate agent, intermediator, intermedium,
   internuncio, intervener, interventionist, interventor, lap,
   lay figure, mediator, medium, middleman, mouthpiece, negotiant,
   negotiator, negotiatress, negotiatrix, nominal head, obverse,
   ombudsman, preface, prefix, priority, proscenium, puppet,
   spokesman, spokeswoman, stooge, window dressing