Ok, I kind of know what they are. If you get banned from digg (or other places), you use a proxy so you can still login... Why are they so popular, and (evidently) make tons of money? And do they really make as much money as these people are claiming in the "sites" forum? I'm lost... Digg must be banning all kinds of people...
they're mainly popular for people at work and schools as sites might be blocked. they can make a lot of money if you know how to monetize them. a lot of time traffic from china/india make up 80% of a proxy, but the ads for those traffic don't pay much. you also see a lot of proxies being sold this time of the year since schools are out. they all take a huge hit during summer vacation. other then that, they're a good investment