The Silkscreen family of fonts was designed by Jason Kottke and is distributed at 
http://kottke.org/plus/type/silkscreen/

The terms of use for the font are taken from the website as of March 11, 2013:

What are the terms of use for Silkscreen?
You may use it or distribute it as a freeware font on your site, but just don't
claim you made it. You may not modify and then redistribute this type family.
You may, however, modify it for your own personal use. You also may not charge
any money for this font.