I've been a happy user of Trillian, the instant messenger client, for about six months. I finally sprung the $25 for the Pro version. Trillian Pro has an RSS plug-in that delivers blog content to your IM client. The way it works is a bit funky and it's not as configurable as I'd like, but it seems pretty nifty.
Trillian is fantastic software. Clean and simple instant messaging, no ads or annoying crap. And it interoperates cleanly with all the major IM networks. The free version 0.74 skin stuff is silly, but Trillian Pro has a good no-nonsense default look. Lots of usability points are high: it imports your contacts from other IM networks with no fuss, autopatches nicely, etc. Excellent piece of software.