I would like to be able to block certain IP addresses from registering on the counters.

This feature is available for Premium accounts. If you have a Premium account, login to your stats page and choose "account options" from the "options" menu. On this page you'll find a text box for IP address that you'd like to block. You may add as many addresses as you'd like, with each address being on a new line.

If you would like to block a whole group of IP addresses, try using a partial IP address.

i.e. 64.34.45. will block all IP addresses that begin with these numbers, but 64.34.45.5 will only block that particular IP number.

Similarly, you can use the "Domain/Host Filters" box to block out certain domain names.

These filters work right to left. So,

.com

would block all .com visitors and

aol.com

would block all aol visitors.