Rarely do I have a formal contract with my clients, but in general I ascribe to the principles of the AIGA standard agreement, intellectual property exclusive license, and interactive specific terms and conditions where applicable.
Chief among these is the language pertaining to Copyrights & Trademarks, Limited Liability, Indemnification, Design Credit, and Nondisclosure. I also stipulate the following in regards to ecommerce.
Laws Affecting Electronic Commerce. From time to time governments enact laws and levy taxes and tariffs affecting Internet electronic commerce. The Client agrees that the Client is solely responsible for complying with such laws, taxes, and tariffs, and will hold harmless, protect, and defend Developer and its subcontractors from any claim, suit, penalty, tax, or tariff arising from the Client’s exercise of Internet electronic commerce.