While talking to the team at UK based Talenetic last week I learned of a great way that one of their customers, TopEngineer.com boosted their job alert signups by 19%. Check out this screencast.
They placed the box after every 10 listings. Smart move. If you have the ability to insert more subscribe boxes into your result this tip will certainly boost your subscribers. Job board software companies and applicant tracking vendors could also learn from this tactic.