Contract Sign + Advanced Invoicing
A one stop for clients to sign their contract electronically and make payments with credit cards. I currently use the invoicing feather and love it! Would love to really see this developed into a one stop of my clients to make their payments and review their contract.
lori cannava commented
Shootproof offers contracts and invoices that can be customized and signed electronically before a shoot.
We actually already allow contracts to be attached to invoices. :)
At the bottom of the invoice area there is a section for you to upload your PDF contract(s). When your client views an invoice that has an attached PDF, they can view/download it right from invoice details page and they are forced to click a box saying that they agree to the contract before they can submit their payment.
One warning with this though: although electronic signatures are technically legal and just as binding as a written signature, if you ended up getting a chargeback on a contract that was signed electronically it would be significantly more difficult to fight than if there was a written signature on it. At least that has been my experience with them.
I'm not sure if that is what you were looking for, but it sounds like it may be close!