Sorry for not posting here in a while. Starting a company definitely cuts into the time that you can spend on blogging. I don't know how some of the really prolific folks do it!
In particular Yahoo has been on a tear and I know that there are a few more APIs that are going to be released soon (hopefully before the new year) so stay tuned.
Here are a few more APIs that have been added to the wiki:
Aggregate Knowledge - Add behavior based recommendations of items to your web site
Amazon Mechanical Turk - Get humans to do things you want by paying them
CoregMedia - Lead Generation / Co-Registration Network API
ecommStats - Get access to web analytics through the APIs provided
Rhapsody - Let's you play music through the Rhapsody website
Yahoo Traffic - Traffic Information from Yahoo!
Yahoo Local - Get access to location information and reviews about things in Yahoo's database.