I did a survey, it saved a cookie on my hard drive, I deleted the cookie, and it did bring up the survey again. I also looked at the cookie and this is all it said.
I took the surveys in IE, and they came up again when I tried Netscape, so whatever blocking they're using isn't across browsers.
The Obtuse Angle (wienerboard.com) <- No kidding, right? Buffy 7.19 gets a 8.33 Cat fighting! Clem! Curly Fries! Faith dancing! It's a bumpy ride to the end. Next week: Faith and Wood? Ech.
Absolutely sounds cookie-based then, exactly as InVerse suggested. So probably quite acceptable from a privacy/security perspective. (Although really easy to defeat if'n you did want to vote 5,000 times. ;-) )