del.icio.us is a social bookmarking website -- the primary use of del.icio.us is to store your bookmarks online, which allows you to access the same bookmarks from any computer and add bookmarks from anywhere, too. On del.icio.us, you can use tags to organize and remember your bookmarks, which is a much more flexible system than folders.

A well-known site, in my opinion. I like it but it's pretty bare bones. Everything there works fine that I've used.