I really like BigNoseBird's polling script (and not just because of the name ). It lets you use either IP numbers or cookies or both. It's not perfect, though - we recently ran some polls that, on some days, were getting a couple thousand responses an hour. The script invariably crashed, maybe when two votes came in simultaneously, and wiped out the basic config/results file (fortunately, the script also logs all the votes, so using that we were able to re-create the vote tallies up to the crash time).