Buddywave is a free Windows-only browser, based off of Internet Explorerwith some MySpace functionality built in. You have access to a MySpace profile builder (which is incidentally the same one we covered in our Mashcodes post) and a messenger that lets you create groups and manage your MySpace friends more effectively. There's also the ability to instant message and a picture viewer.
I'd prefer Buddywave be an extension or toolbar, as I've gone so long using Firefox, it would literally cripple me to use a new browser--especially just for MySpace use. However, Buddywave might be the first real application to address the problem of friends management and communication for what's obviously become a rather taxed element of the popular social networking site.