I'm fresh and new to theme-ing so I haven't encountered this yet, but I'm sure it will happen, eventually.
Since I released under the Creative Commons license, if I find it I would probably send them links to the CC license they signed up for and tell them they signed up for it. I know some people do it on accident by not uploading a custom template with a theme, or reverting them to make it compatible. So I'd start giving them the benefit of the doubt, maybe it's just because it hasn't happened to me a billion times yet.
Hopefully, that would make them scared and replace the link or use another theme.
Then, I'd go to phase two of joining their forums and posting about the situation in their own forum.
If it still happens, I would google up their username and try and find other sites they've joined. I'd send the user a PM on every account, and post in the forums about the situation, the moderators would probably at least temporary ban the person from the sites.
If it really continued, and I doubt I myself would go this far, since I released under Common Commons, I can use that binding agreement as grounds for legal action.
Since I released under the Creative Commons license, if I find it I would probably send them links to the CC license they signed up for and tell them they signed up for it. I know some people do it on accident by not uploading a custom template with a theme, or reverting them to make it compatible. So I'd start giving them the benefit of the doubt, maybe it's just because it hasn't happened to me a billion times yet.
Hopefully, that would make them scared and replace the link or use another theme.
Then, I'd go to phase two of joining their forums and posting about the situation in their own forum.
If it still happens, I would google up their username and try and find other sites they've joined. I'd send the user a PM on every account, and post in the forums about the situation, the moderators would probably at least temporary ban the person from the sites.
If it really continued, and I doubt I myself would go this far, since I released under Common Commons, I can use that binding agreement as grounds for legal action.