There's a new currency system out there – Pay With a Tweet. Instead of paying money for a service or product, you can pay by tweeting about it, thereby giving the provider exposure. On the flip side, you can offer something to consumers in exchange for their tweeting about you. It's an interesting system created by a couple of guys in New York City. There are a few rules – no inappropriate language in your tweet, for example – but otherwise, it seems like a straightforward way to build social media buzz.
These guys are not the only ones trying to make money from Twitter. TwitPub is a service that allows content providers who keep their tweets private to sell premium subscriptions to those who want to become followers. Magpie provides an advertising platform for marketing campaigns of all sizes.
Twitter is clearly popular, which naturally incents entrepreneurs to seek ways to profit from it.