Adding Tags to Comments

I’ve searched through the Support and Forums and can’t seem to find anything on adding tags to comments.

I’m wondering if anyone else has had a similar request. I will be working on a project that consists of a predetermined number of posts on a WordPress blog, users will be asked to comment on these posts and I wanted to have a Tag Cloud generated off tags in the comments.

I know comments don’t generally have tags, so I’m wondering if this is possible, feasible or if someone could point me in the right direction.