With the widening audience of users that eBay, Skype and PayPal all have, and while those users may become more casual customers than rabid early adopters, the recent addition of StumbleUpon to the eBay family may be a key that holds the keys to even more treasure in the chests.
Basically StumbleUpon is a 2.0 style search engine, but has enough hooks in it and personalization/relevancy tools that makes it something that can integrate into Skype rather simply.
Russell Shaw shares his thoughts on this here.