With my modem, every time I switch on I get a new IP number.
My previous modem had a help-menu desktop icon and there was an option there for changing IP.
And I'm sure the technically-minded amongst you have plenty of other ways of changing the IP number for your system.

So why does this matter for our toplists? Multiple voting that's what.
I've noticed that a change of IP and deleting cookies allows someone to vote for a site as often as they like.

I have at least one site that I am sure is using such means of multiple voting but I'm blowed if I know what, if anything, can be done about it.
After all - even if I could do something about it, like banning a whole range of IP numbers - do I really want to cheese off my most active sites?