I agree that editing the hosts file is by far the best thing for actual adblocking, but I like to have a manual adblocker in the browser, too. Not actually for ads, but so that I can "turn off" parts of pages that I don't want to deal with easily (for example, annoying, gross or animated avatars at forums).
this guy has a collection of blocked ad sites in this hosts file :
http://zelut.org/projects/misc/hosts
btw windows has a hosts file too ;)