If you want to build really useful software that is usable in harsh ( office/university ) envoirment, you need to build in NAT traversal. Something that will enable users behind routers which can only use http for internet connection. They have disabled TCP ports, and similar stuff. This is a week spot in every P2P application, and I think that there is a lot of people with this problem. There are plenty of university networks, all firewalled/disabled for everything but HTTP. So... I think it is a good idea. :D
