I don't use bookmarks, or hardly ever. I use multiple browsers on multiple platforms and there's no good way to centralize my bookmarks.
I use iGoogle's bookmarks widget for the website's I visit daily and I favorite things inside those web services (like favoriting pictures here in Dailybooth, tweets with cool links inside twitter, etc.)
I also memorize a ridiculous amount of URL's, but that's just me I suppose. I don't use a bookmark for actual physical books I read either, I memorize at what page I am. Currently page 247 of Antony Kiedis' Scar Tissue, if you're wondering ;)