An online TOS is not worth anything <i>unless</i> you can prove to a judge that the user did indeed read and agree to that <i>exact version</i> of the TOS.<p>For example, a user can edit the html, print it out, and claim <i>that</i> was what he agreed to when he signed up.<p>Or, after getting involved with a user legally, the website can alter the TOS on their site to better their own position.<p>Even if you register with a 3rd party (we get the police to date and verify with a signed document everytime we change ours by making them visit our website and printing off the TOS) - however that still is suspect to tampering.<p>The best way is to make the user print, sign and return the TOS.