I can't tell if you made a border for it or not, there's a portion of it that doesn't look like you did.
Remember: Border's add the "finished" look ... besides the text, I would say it is one of the most important parts of the sig.
Easy way to apply a border:
(If using Photoshop)
Create New Layer
Move it to the top, if not already there
Click - Select > All
Click - Edit > Stroke
1 px > Black > Inside
... and ... walla! Simple, yet effective border.
As far as the sig goes ... I would try some lighting effects on that background as well as darkening it.
Work with some brushes and shapes to get your desired effect.
Go Here: DeviantArt.com
- in the search blank, type: Grunge Brushes
or Fractal Brushes
or Tech Brushes
etc. (you get the idea).
When you find the brush you like, click download to desktop.
If the file comes up as a .abr extension - just choose to save it to : C:\Program Files\Adobe\Photoshop CS2\Presets\Brushes
Same thing as if it's a .zip file - just extract to that location - or whereever your PS file is located.
Hope some of this helps ... good luck, and great start!