When a user edits, we request a cookie "usertoken" or whatever. If they do not have one, we generate a long random number and give them one. Every edit made by that browser (no matter which user is logged in) the cookie is returned. We add an extra column to recent changes to store this value. A new version of sockcheck is produced that finds users who share revisions with the same token, much like we can do with IPs already. Viola, cookie based sockcheck. Thoughts?