Very unlikely, I think. How many AOL users are there out there?IPs for dialup users rotate, so if you have 20 people from AOL visiting your site, you might end up with one who can't vote because their IP at the time matches what someone else had at the time they voted.True, but there's no other way, barring logins, which are too much hassle for the average poll-voter.Logins are the only sure way. Aside from that, IPs are good, but if people wish to cheat, they can go to another computer.
simonf: Since server-side scripting will be required anyway, cookies should be sent in the HTTP headers. This is much more reliable than setting a cookie using client-side scripting.