Current Account Mortgages, also known as Offset mortgages basically allows you to the savings you have from the capital element of the mortgage.  There are various methods in which this can be done, but usually by opening up a current account in which your income is paid and outgoings taken out of.
The balance on this account is deducted from the capital balance of your mortgage with interest calculated on a daily basis.
This is ideal for a current account mortgage account holder who is disciplined with their savings to potentially achieve lower interest repayments.  Current account mortgages or Offset mortgages may not be suitable for everyone.  However, for those with savings or a surplus amount of income, they certainly have proved to be a fast and cheap way of paying off a large mortgage.