Messenger Plus! has to be one of the coolest plugin/extensions I’ve seen for a product in a long time. If you use MSN Messgener, get this. A full list of the features is here. Customized away messages (with automessages) is worth it alone.

Update: Looks like the install for this might put some hijack-ware on your box. I selected “NO” to support sponsors, and haven’t seen the problem. Looks like there’s some details here.