I’ve been a very happy use of Foxmarks over the years for keeping my bookmarks in FireFox up to date. Turns out, they’ve renamed themselves to xmarks I guess so that people don’t assume they just do Firefox.
Basically, the way it works is you create an account on their server, then for firefox you download a plugin, and for IE you download an extension. Like magic, your bookmarks just stay in sync!
Another nice things is you can manager your book marks on line. The Xmarks folks used ExtJS (my favorite JavaScript library to build their interface, and they did a very nice job).
One thing I find a little unusual is it asked for a $5 donation. I noticed that Mitchell Kapor is the founder (also inventor of Lotus in 1982). I have trouble believing he needs my $5.