The only manga I've read were the original Drangonball books back as a youngster. I haven't touched the stuff since. Although, seeing as I'm just now getting into anime seriously... I'm sure manga is jut around the corner.
If you need further proof of the awesomeness of Highschool of the Dead - look no further than this:
http://www.youtube.com/watch?v=cNtlMjRqfQs