Top lists are your best bet, but to work your way up you need to offer a fast reliable service that is consistent over time. If you're using a perl based proxy, make sure you get mod_perl installed and configured on your apache, or you'll see your server grind to a halt. Enabling mod_perl brings my peak server load down from 200+ (totally unusable - can't even log in to ssh) to about 2 or 3. mod_perl is NOT compatible with cpanel/WHM!
Also, running a proxy will chew bandwidth like there's no tomorrow.