Every time people bring this shit up, there's still one or two that aren't educated.
www.proxypass.com
Get it, love it. It does everything that pennywize and IProtect do (with less server load) PLUS stops open proxies from accessing your site at all. It protects us very well, and is configurable as hell.
I don't own the company, have a stake it, or anything like that, I just like and use the software.
Cheers,
Backov