Question about rating systems

[eluser]KeyStroke[/eluser]

Do you mean since people do not always have a fixed IP address? Therefore, if they turn off their router and connect again with a different IP they could always vote again! And if another person came along and happened to have an Old IP from someone else who voted they cannot vote?

Exactly!

and it's a public voting system where people vote on various items on the site, so I can't e-mail verification since they're supposed to vote on the fly.

What do you guys suggest?