Common examples include words like "you agree to re-check the terms every time you use the site, since we modify them from time to time".

• (This might have been struck down once, years ago, in the 9th circuit, but I don't know its current status really.)
• There are easy technical workarounds to this: email in advance when terms change, and *what* will change, and prompt at next login.
• And/or provide a "last changed" date AND show *what* changed each time, prominently at the site itself.
• Any software developer should know (or can learn) how to export a document as plain text, run a "diff" command, save the output, and save a revision history!
• If not, or if you want a shell script to use as a consumer to compare versions, email me via the footer of this site, and maybe I can help.