Not thought about these much, but I have them jotted down on my ever-growing ideas list. They're a bit dated.

1. Bluetooth analytics. A lot of people are broadcasting their BD_ADDR and don't know it. Give shop owners some way to see recurring visitors - or perhaps even track how they move around the shop.

2. P2P file distribution for businesses. Your users install a client and get paid a small amount per hour (which changes depending on demand). Businesses needing to distribute a large file pay you to host it on your 'botnet'. I don't think ISPs would like this an awful lot.