Well said Kappacino,The site would obviously have to take into account the buyer's location when showing the prices as well as their home currency.I was doing some number crunching today and looking at the relative purchasing power of the dollar versus the pound and saw that at current MtGox rates you'd have to pay an extra GBP 2.40 to buy USD 150 worth of Bitcoins compared to someone using dollars.To some extent you can hedge against this by selling your Bitcoins for a USD dollar amount on MtGox thereby keeping a reserve but of course you do lose out on the initial sale of Bitcoins and you'd have to have money to spare. An alternative would be to peg prices to the average purchasing power of a basket of all three currencies USD/EUR/GBP as per MtGox which would also mean they fluctuate less. It would still be possible to show prices in the user's home currency.V.