Wathsala has recently blogged about the architecture of Dalaesa and the DCache application - a distributed, peer-to-peer Web cache which is an alternative to Squid-like centralized caches. The architecture figure Wathsala drew is the following:
There are lots of potential applications that can be built on top of a P2P application framework. The DCache was basically a POC .. to show that the lower layer works. Other more interesting apps include building autonomous security boxes that mesh together and provide a P2P monitoring layer. Have ideas? Contact Wathsala and join the project!