I briefly mentioned a demo app built within my team that integrates Outlook with Flickr (I think I mis-identified it as Facebook in the original post). It's in that category of apps that I'm not sure the "OBA" label fits but is more of a convenient mashup of Outlook and web services.
This was developed by Adam Wilson who is doing an internship on the VSTO team right now. It is pretty simple. First it extends the contact view in Outlook by adding an adjoining form region at the bottom of the contact view to associate a flickr user name with a contact. I've doctored the screenshot a bit to protect the innocent.
Then, when you click on a mail item from that contact or any other contact that you've associated a flickr user name with, it displays the most recent pictures posted to that user's flickr site. You can see that Adam created an adjoining form region that displays in the reading pane for mail items. Also, he used a cool WPF control to get the nice reflection effect for the photos.
This type of application is super easy to build with VSTO Orcas which has support for easily building Outlook form regions with a nice wizard and a cool Windows Forms based programming model--a subject for a future post.