I've started playing around with developing gadgets for the new windows side bar...
I found a great list of resources to develop for these things...
http://microsoftgadgets.com/livesdk/index.htm
I'll go into them a little more once I have finished what I've done... But so far I like what I've seen...
EDIT:
I got an email from Daniel Moth last night letting me know of a little boo boo I made, the link is clearly for Live Gadgets, ones you can add to your Live.com page. Opps Sorry... He was kind enough to pass me this link of his work in this area as well. Good man sir...