1. A computer-implemented method of processing a transaction comprising: receiving, at an intermediary computer, from a client device associated with a first participant in the transaction, a request to process the transaction using a first currency that is not recognized by a second participant in the transaction, wherein the client device is operatively connected to the intermediary computer via a communications link, and wherein the first currency comprises a private currency; decrementing, by the intermediary computer, an amount of the first currency associated with the first participant by decrementing a balance of a first currency account of the first participant maintained at the intermediary computer; incrementing, by the intermediary computer, an amount of second currency associated with the first participant by incrementing a balance of a second currency account of the first participant maintained at the intermediary computer, wherein the second currency is recognized by the second participant; and processing the transaction using the amount of second currency associated with the first participant; wherein the amount of second currency incremented by the intermediary computer is determined based upon at least a set of one or more conversion criteria; and wherein the set of one or more conversion criteria includes a time at which the request from the first participant is received.