I can't say a thing about the big proxy servers because I'm pretty ignorant there, but if you can just automatically stop/delete the votes coming from the same, identic IP, without a major filter, then a lot of votes pass. almost all the ADSL IP are dynamic, not static. I have a 24/7 contract, so as soon as I turn the modem on, I'm online. I don't use the connecting window (the one with your username and password), so I pretty much have the same IP for the whole session. But if I use my ADSL connection window, 9 out of 10 times I disconnect and connect again, I'm going to be assigned a different IP, although they usually give similar sequences of numbers to the connection of a same area, so 1 or 2 or the 4 parts that rapresent a IP can be identic.