Assuming you know the url to use anyway. Courtesy of Digg, go get started with Google Notebook. This is immediately useful to me and will displace my personal wiki for some of the kinds of things I end up dumping into it (things to blog, for example) and also will displace some of my uses for the social bookmarking sites. Note that you’ll need to already have an account with google, and you’ll need to be using Firefox because it installs a (very slick!) extension to firefox that makes it drop-dead simple to dump content into your notebook.
I suppose I should explain what this is – it’s an online notebook that you can dump text and urls into. It’s sort of a combination of a bookmarking tool and an online note taking tool.