Xmarks is a plugin for Firefox, Chrome, Safari and Internet Explorer that can automatically synchronize your bookmarks across multiple computers. I have used it for longer than any other Firefox add-on I use. It’s very useful for me because I use the same software on my home computer as on my work machine; 3DS Max, CS4, etc. Whenever I find a resource at work that I could use at home, I bookmark it on my work PC and it automatically syncs with the bookmarks on my home machine. Same goes the other way around; when I’m surfing at home and find something relevant to work, I don’t have to email a link to myself, I just bookmark it. Very handy!