WordNet (r) 3.0 (2006):

straw vote
    n 1: an unofficial vote taken to determine opinion on some issue
         [syn: straw vote, straw poll]

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "straw vote":
   Australian ballot, Hare system, aye, ballot, barometer, canvass,
   canvassing, casting vote, counting heads, cumulative voting,
   deciding vote, division, enfranchisement, fagot vote, feeler,
   franchise, graveyard vote, hand vote, list system, nay, no,
   nontransferable vote, pilot balloon, plebiscite, plebiscitum,
   plumper, plural vote, poll, polling, preferential voting, probe,
   proportional representation, proxy, random sample, record vote,
   referendum, representation, right to vote, rising vote, sample,
   say, secret ballot, show of hands, single vote, snap vote, sound,
   sounder, suffrage, transferable vote, trial balloon, viva voce,
   voice, voice vote, vote, voting, voting right, weather vane,
   weathercock, write-in, write-in vote, yea, yeas and nays, yes