Short answer, since that link is nice and in-depth: They are beloved patriot home routers, many can connect through one system. They work differently though, a program has to know that it needs to access through the proxy. Special features include caching, to reduce bandwidth usage. Good for people with several systems on low end DSL and dialup. sed by @Home by default.
It's kind of funny actually, @Home techs always try to tell me how much faster the damn proxy is. It's always overloaded though, slow, and it bugs me that it can be used to monitor my usage very very easily. Not to mention that I'm still depending on my poor little cable modem just as much, and most stuff I view isn't so static.