Hobnox is a very cool alternative to sites like MySpace (not the name of a new biscuit) where you can upload files (music, photos, video), create a blog, make contacts, send messages and view everyone else's content. The main difference is that the site appears to have been designed by "creatives", people who work in the creative industries, and is consequently beautiful to look at and very exciting to use. As well as a kind of online TV channel, there are interactive elements like the Audiotool that allow you to create amazing electronic compositions.
It's hard to describe how good this site is so I strongly suggest that you head over and take a look. I've had a go at creating a profile, uploading some photographs (which I have made available using a Creative Commons license to anyone who is interested) and making a tune. If any of you manage to create a really good tune using the Audiotool application, post the link in the comments section.