A crash course in changing the world.
I find it fascinating (and very sensible) that communities in Africa are using cell phone minutes as a medium of exchange. They can be bought abroad and sent home simply, and the funds can be exchanged with text message.
Add to this two things:
One, there are several exchanges out there which set value for things like WoW gold, Farmville bucks, etc.
Two, Paypal's software is open source.
Combine these things in a pot, stir, and this is one possibility.
Make cell phone minutes in the US tradeable on exchanges, and accessible via cell phone, possibly with a Paypal (or similar service) back end. US consumers could buy minutes and transfer them to accounts which convert them to dollars. They can then use their cell phones to make transactions at stores (which have an internet connection or a phone of their own), and manage the account electronically. An instant banking option for the first world, with fewer barriers of entry than banks. All you need is a cell phone (a prepaid phone would do), and willingness to set up an online account.