I am working with a client currently who is trying to implement a type of “Terms of Service” that requires different revisions of the terms to be available.
For example: If we update the terms, a user should be able to view the version of the “Terms” they last agreed to as well as the new terms (to view the differences in each version, and because they may not be required to accept the new terms, while still being bound by the old terms).
I have not been able to find any kind of Terms of Service plugin that offers this. The closest I have found is http://wordpress.org/plugins/terms-of-use-2/ which forces users to re-accept when you update the terms.
I thought this would be a useful feature to be available, so websites can better track their Terms of Service over time instead of just updating them.