A problem I see quite often over on SharePoint.SE is a new or reasonably low-rep user posting several links to their own blog or site (as tangentially discussed here); either as an answer or in their (inappropriate) signature.
Usually their affiliation is undeclared, through deception or ignorance.
These usually show on the Review pages under First Answer or Low Quality Post, but it takes some investigation to find out whether this is actually their site (linked in their profile) or most likely their site (several links in different answers to the same site).
Would it be possible to add a page that flags lowish rep users that have linked more than once to a particular site (I imagine this would need a whitelist of some form)? And/or where their profile link is the same as their answer link?
If you were feeling really fancy you could even add a quick declaration check (I'm going to use the word 'heuristic', even though I only half understand it), for phrases like "my/our article/blog/site/product".