do you like my signature?

Like it , maybe a bit too high to use on forums, but that's personal flavor .

Yeah it seems pretty high (vertical real estate). Nice though. I like how the person conveys action. I wouldn't hurt to crop off the top of the head (15-20 pixels). Then do like a invert bulge (I don't know the tool/effect) this would simulate a fish eye lens refraction. You can then get more of a tight composition of the action/person. Then enlarge the Lettering in the lower left. You could also add some depth to the text or your logo. Maybe a Gaussin Blur as a shadow. The if you know how to do this, create a sweet spot, like a short depth of field view somewhere in the background. Then while your at it you can go for an SI (Sports Illustrated) look by adding more contrast to the image and a slight tint.

This is just a suggestion, I hope I'm not to critical. Looks cool though.

Oh yeah what program did you use, and about how much time did you take, and what's part took the longest to do? I'm curious.

My personal opinion seems to match the other two posters about the height. It could quite happily lose a quarter of its height, maybe a third, it just seems to chunky at the moment. As for the actual image itself, well beyond my ability with photoshop and the like. I'm shocking at playing with graphics, except for vector-based art. Nice work, nonetheless.