I think there should be a random comic button. When a person would click it they would be brought to a random comic from the site.
The button could possibly be a tab in the top banner. or maybe another tab you find after you click the comics tab. (I think the first option would be better so that if someone uses the button and wants to find a different comic they would not have go through to comics section again.
I love to read a variety of comics, and this would help for me to find ones that I would probably not have found any other way.