Here are some tiny fonts I made a while ago, they are all released with a Public Domain licence, meaning you can do whatever you want with them.
Minimal4: A simple 4 pixel tall font, a bit hard to read, but can be useful in a pinch.
Minimal5: A slightly bigger font, 5 pixels tall. I use this in a lot of my tutorials.
Monocons: A 6 pixel tall monospaced font, useful for some making an oldschool console.
If you want more (and much better fonts) I highly recommend investing in Chevy Ray’s font pack.