Option to not store IP addresses

An alternative could be to hash this data in the database? It could be a general setting that applies to all polls on the site.

However, I don't think storing IP addresses is a privacy concern as they don't really tell something about the user.

For example the webform module is also storing IP addresses with each submission. It does have a setting to disable this (on general level for all, or per webform setting).

They are doing unique checks in a different way as us. They check on UID or a cookie value.

Which is essentially what the anonymous voting issue does, it adds ip/session/nothing as options, so once that is done, then this could be implemented on top of that if an option other than hostname is selected.

Aah yes, totally forgot about that one when going through the backlog :) linking it together helps!