What happens if I mistype the address when making a payment? I sent bitcoins to an address, but I think I made a typo when I copied it. Where did these bitcoins go. Can I get them back?
Bitcoin is very resistant to typos because the addresses contain a built-in check code.  So if you had simply mistyped a few of the letters or numbers in the address, it's unlikely the client would have let you send them.  If, however, you pasted in a different and valid address, the coins are already transferred to it permanently.  In this scenario, Bitcoin works pretty much like cash--there is no way to get it back after giving it away.