On a pure design side, it’s really not that bad.
You could make navigation a bit more attractive. Using another color than black would be a good start (especially when dealing with a dark grey background).
As Melindrea says, try improving the font. Pick a sans-serif font you like (Helvetica Neue, Source Code, Open sans, etc.) and use it for all text content across your site (except maybe headings). Also, choose a much much bigger font size.