Buxter, a Facebook app that launched just a few days ago, enables Facebook users to transfer, receive and request real currency (US dollars or euro) from other users free of charge.

The app, created by London-based payments provider ClickandBuy, enables payments of up to 50 euros, or $68. Sending and receiving money is free, but ClickandBuy charges a 1.9 percent withdrawal fee, with a minimum withdrawal of 2 euros, or $3.

While handy for settling a dinner or drinks bill between friends, it’s only really valuable if all your Facebook friends use it and it becomes the norm for small, personal payments.

A money exchange system more likely to succeed, given its ubiquity, is Facebook Credits. Facebook Credits can be bought with a credit card and are used to purchase virtual items within games like FarmVille. They can also be used to buy virtual gifts for friends. By providing a single, cross-application currency, Facebook’s goal is to making transactions simpler for users, leading to a higher conversion rate for developers.

While still in beta, the likelihood of Facebook expanding the use of Facebook Credits is very high. A February Blog Update reads, “We are committed to investing heavily in the ecosystem and will explore a number of ways to improve the program and increase conversion and net revenue for developers, including user education and marketing, testing innovative ideas such as bulk discounting and seeding Facebook Credits to drive discovery and repeat engagement.” It’s widely believed that the full launch of the service will come at Facebook’s F8 Conference in April.