Pixel Font Guidelines
http://www.miniml.com/fonts/guide/index.htm
MiniML fonts
http://www.miniml.com/
on the right side check for "free".
win mac
more...
http://www.dafont.com/bitmap.php
Most pixel fonts do only work with a size set as a multiple of "8"! So font_size = 8, 16, 24, 32, 40, 48 etc.