>This reminds me of a friend of mine who proxies all his web traffic through something which strips user agents and referrers. It's very easy for me to tell when he visits my website, because the logs show "-" for each of these fields.

I wonder if the best strategy, then, is to figure out a very common user agent string and use that. The EFF's Panopticlick might be a good start: https://panopticlick.eff.org.

> It's very easy for me to tell when he visits my website

Simply drawing attention to the fact that his attempt at anonymity acts a key personal identifier in this instance.

That's really interesting. It sounds like an easy way to get targeted by the people who do want to track you, though. Still -- do you have any idea what he uses for that?

How does your friend do that? I'd be really interested in reading on how to setup a proxy like that.