i have used xmarks for a good while now. it used to be called foxmarks. it basically keeps a list of your bookmarks on their server and syncs them with your browser. not impressive if oyu only have one computer and use one browser, but when you use 5 computers and 3 different browsers on each having all your bookmarks and passwords in sync is an amaising accomplishment.
just go to it in your ‘main’ browser and download it, follow the wizard and you are set. then go to xmarks.com in your other browsers and do the same thing. you can merge all data in each browser with the data on the server to keep a master list of bookmarks, or you can overwrite the data for that browser with your master list, etc.
try it out. you wont be disapointed. if you use t with safari then your bookmarks also go onto your iphone or ipod touch. which is nice =)