While working at eBay Research Labs I did some work using Skype that resulted in four patents in the area of P2P trading and reputation systems. I just noticed that they are now public, as of late 2007, and here they are:
Peer-to-peer trading platform
Peer-to-peer trading platform with relative reputation-based item search and buddy rating
Peer-to-peer trading platform with search caching
Peer-to-peer trading platform with roles-based transactions
The seed of the idea came from my good friend Josep Ferrandiz, who still works at PayPal. The ideas were developed with help from Zahid Ahmed who is now working for EMC, and with a lot of help from Neel Sundaresan who manages eBay Research labs. The patents are in all of our names.
I think we came up with some cool ideas, we also stress tested the Skype API's in some novel ways and got some things fixed. The lasting legacy of this work is more robust application to application messaging API's and improvements in Skype4Java.