I did three quick posts on Ping lists (list included), Directory Submissions (list included) and restricting low yielding ads through the competitive ad filter on your Google Adsense panel. The first (ping) and last one (competitive ad filter) certainly work, the one in the middle (directory submissions) I am not sure about. But feel free to try your luck. Here are the three short and sweet posts and the three lists.
The search for incremental traffic – WordPress ping lists for your blog
Directory Submissions list – a possible tweak to generating more traffic
Google Adsense – Increasing your Adsense yield through the Competitive Ad Filter
Chandoo’s success: A must read; the guys earns by selling Excel templates and trainings!!