The peerless Steven Frank, who is pictured on the right as he depicts himself, draws Spamusent. He describes it as "poorly-drawn cartoons inspired by actual spam subject lines."
Although obvious once he invented it, the idea of illustrating e-mail subject lines is überclever. I hesitate to say that it is a more original and fertile cartoon gimmick than having ninjas fight, but it is in the same league.
In the Spamusement forum, he challenges visitors to draw spam-subject illos of their own. I've drawn a few, and this webpage is here to keep them collected together.