Hey wanted to contribute what I found last week and it works wonderfully! My mechanic actually turned me on to this when he came to fix my car and I didn't have cash on me. Its called Square. Its a credit card reader and processor for your phone. You just swipe it and it shows the screen for the client to sign on the phone with there finger or one of those pin thingies and that's it. Money was in my account in 2 days. A little cheaper than paypal. And I also like that you can key in the number as well even though the fee is higher.
That way you can get a client to sign a credit card authorization and just punch them in monthly with the contract too. Anyway for those who want to try it out, their site is
http://www.squareup.com