PayPal is an alternative card service to the big banks and a number of traders have taken it up as their preferred option.
PayPal don't charge monthly fees but instead opt for a 1.95% fee on the value of the sale. That is generally higher than the banks although the bank's considerable monthly charges do mean you need to do your sums to work out which is best for your business.
PayPal have just introduced a Tap'n'Go card facility which narrows the comparison even further.
More details here - PayPal Tap and Go.