Blueberry is a tiny, 5x10 bitmap font, made with gbdfed, designed to be clear, and as small as possible.
Make a ~/.fonts directory if you don't already have one, and cp blueberry.bdf into ~/.fonts
Then, to add it to the system:
mkfontdir ~/.fonts
mkfontscale ~/.fonts
xset +fp ~/.fonts/
xset fp rehash
fc-cache
Check xfontsel to make sure it's there, it'll be under the foundry Arathnim.
To make it so fc-list and fc-match can find your font, you'll need to do XML magic in ~/.fonts.conf.