First of all, you will need to verify yourself (mobile phone SMS, drivers license / ID, etc) and then you will be able to get a bitcoin credit card. You will need to pay a fee depending on the credit limit - if you want a credit limit of 10 BTC (for example) you would need to pay 5 BTC up front in fees.
Why would you do that? Well, let's say you get paid in the 1st and 14th, and it takes a few days for you to get bitcoins on mtgox after a bank transfer. You want to buy something on the 8th. Pay it back in 30 days and no interest
Would anyone be interested? It's not going to be an actual physical credit card, just a wallet where you can spend more than what you actually have.
