If you've ever wanted to watch streaming video right on your desktop, and organize all your favorite streams in a single bucket, it's worth checking out StreamDesk. This cross-platform desktop application plays video streams from a variety of sources in a simple player that cuts out the browser completely and turns each show into a small, floating window.
Included are more than 100 various streaming video shows from a small handful of providers. If you come across one that isn't live, you're out of luck, otherwise live shows begin to stream in almost instantly. Shows you like can be bookmarked into a favorites list, and each has its own button that takes you right to its source page.
There's currently no way to add your own shows via URL, however the catalog is updated frequently and you can make suggestions for new streams by e-mailing the developer. Also, on StreamDesk, you're missing out on the integrated live chat on videos that are coming from UStream.tv.
If you're a Mac user you'll need to be running OS X 10.5 (Leopard) along with the latest version of Flash 10. Windows users need Flash 10 as well, along with .Net Framework 3.5.