This was the easiest of my icon requests so far, so I knocked it out first.
The classic batman logo for stuffnjunkmose. Of course, anyone else is free to use them as well.
I ended up doing two versions; pick whichever you prefer.
First, I did the bat logo by itself:
This is available at http://userstyles.org/styles/73105/batman-home-icon-for-tumblr
Then I thought it would maybe look better with the border around it, so I did that one as well.