Cadmus is a real-time service that manages your stream (Twitter, FriendFeed and RSS) by displaying the most relevant content since the last time you checked in. It helps you get caught up on what you have missed.
AirTalkr is a multi-protocol Instant Messenger that connects to MSN, Yahoo!, GTalk, AOL and ICQ. Not only that, it also has connects to to various Web 2.0 services like Flickr and YouTube. AirTalkr runs on Adobe AIR, so you will need the runtime to use it. As of now, AirTalkr can run on Windows and Mac. Also has Web version