The Tvider service allows you to share anything multimedia on Twitter. You can record right from a webcam or load one of their mobile clients for Blackberry, iPhone, Symbian and more.
Once a tweet is posted with the content, you can zoom in, favorite or mark it as abusive right on the site. The type of media file in shown as is icon in the upper corner of the tweet itself.
Popular tweets and popular members are highlighted on the right. Otherwise the site is quite straightforward.