A digital currency for Microsoft Outlook? Social Networks? WSJ's Andy Jordan talks to currency renegades tired of big-government centralized cash, and desperate to make their own (legal) money systems.  On the new currency frontier are several examples including Ven and Attent are showcased.    According to Wikipedia, Ven is a virtual currency used by members of Hub Culture to buy, share and trade knowledge, goods and services with anyone in the network and can be spent at any Hub Culture Pavilion. The currency is currently linked to the U.S. dollar at a rate of 10 Ven to the dollar and trades against other major currencies at floating exchange rates. Ven first appeared as an application in Facebook on 4 July, 2007. In late 2008, the currency became tradeable to anyone with an email address, making it the first global digital currency to move from an online social network into the real world.   

Attent, whose goal is to create an economy with a scarce new currency (Serios) that enables users to signal the importance of their outgoing email by attaching value.   

Most of the social netowrk currencies are focused on measuring attention, trust, reputation and intimacy.  For the real world, prepaid gift cards can be used to raise capital and barter for services.