A payday loan in Bitcoins! Extremely dangerous, unless of course your pay is denominated in Bitcoin. What do you propose to do if the price of 1 BTC  goes up to say 30 USD or higher between now and payday?

http://bitcoincharts.com/charts/mtgoxUSD#czsg2011-5-1zeg2011-07-14ztgSzm1g10zm2g25zv