Tiny is, I believe, the smallest possible font (in pixel size).
It stands at a lofty four pixels tall (five if you count descenders), yet it still contains all the printable ASCII characters.
Presented here in TrueType format, you can print it out at any size you want, in order to make it actually readable.
If you do want to show it in all its four pixel glory I recommend you render it first at a larger size (9 point worked well for me) and then shrink it down.
