Historically, decentralized services don't get mass adoption because computers or mobile devices are off or unavailable most of the time. They are also behind NAT.
The wireless router is in a unique position. It's always on, it's a first-class citizen on the Internet, it's not very expensive, its ownership is clear and simple, and it often has significant unused computing power. It looks like a major, unexploited opportunity to me.
I'm waiting for some company to take advantage of this opportunity. Think of what this could do for decentralized social networking, file storage, currency exchange, etc. It's quite easy to think of possible server apps; just think of any centralized service and consider how valuable it would be to decentralize it.
I would do it myself if I weren't already involved in trying to build a possibly huge business or two. :-)