Here are a few options, for when you want non-social (anti-social sounded awful) bookmarks.
Foxmarks: Actually a Firefox addon for syncing bookmarks, it lets you access and edit your bookmarks online.
Google Bookmarks: Probably one of the better-known ones. I used to use it before switching to Foxmarks.
MyBookmarks: Although I haven’t tested this, it seems like a good option. (However, at the moment, new signups are disabled.)
Also, although it’s not online, here are a few options for USB drive users: