One way of forming a contract between a website and its users is the so-called "clickwrap" agreement, in which website users manifest their acceptance of the contract by clicking a button or checking a box that states "I agree" or something similar after being presented an agreement. Clicking on a webpage's clickwrap button after receiving notice of the existence of license terms has been held by some courts to manifest an Internet user's assent to terms governing the use of downloadable intangible software.
But to effectively use clickwrap agreements, you need to track everything about them:
When you publish them to your website.
When someone clicks to agree to a clickwrap.
When you publish new versions to your website.
When people click to agree to new versions of a clickwrap.
All of these are methods help with proving that the user actually accepted the agreement. It is also important to keep website legal agreements organized in case a due diligence project would ever come up. Employing some kind of version control and tracking in addition to maintaining good acceptance records are important to maintain and tracking website legal agreements.
PactSafe was designed with all of the above mentioned practices in mind. Check it out at PactSafe.com.