I own a proxy network and I currently promote it in google groups. What other promotion methods do you use?
Also yahoo groups has same thing as google groups. And then also you can search forums and for proxy sites.
I have a web proxy with many visitors using adbrite, but my CTR is really very very low. For promotion I used XRumer, harvested relevant forums and put many posts; but I won't continue with that. Just not enough money to make in that field. This is certainly no recommendation but only my personal experience. Good luck, hope it works better for you.