Report spam button

I can’t find any plugin or script to place a “report as spam” button in my comments section.

The button could simply:
– open a form to report a spammy or problematic comment to the admin
– send an email or store in the db the problematic comment ID ready for being checked/deleted by admin.

I have a lot of comments that are not really spam, but people trying to advertise products/services where they shouldn’t (akismet of course doesn’t work for them).
It could add an extra layer of spam fighting with the direct help of users.

Any ideas on how to achieve that?