It comes with a pretty good set of default filters, and you can get 'customized' sets of filters on the Yahoo group dedicated to Proxomitron. (That's "prox-list" @ Groups.yahoo.com) They have a special set just for Yahoo Groups, for example, that wipes out the advertising and re-arranges the page.
The people on this list are on top of the trends in 'counter measures' and will quickly post new filters if new types of ads show up that get around the normal filters.
[ April 10, 2004, 21:09: Message edited by: Baron Munchausen ]