It used to be that font creation was a popular 'geek' activity, but this is one of the more original ones I've seen.
The idea's quite simple, a font that enables you to type, instead of a normal character, the image of a D4. Naturally, you might have a D4 with rounded or sharp corners, never mind the permutations of which numbers are showing and the various different arrangements of numbers on the die that are possible - is it the top you read or the side it landed on, and the like. They're all here.
To use, you just install the TTF file with the other fonts in your word processor, then access the image you want by selecting the font and then the correct letter on the keyboard (hence the PDF character maps for ready reference). Why you might want to do so is another matter - you probably won't have read this far unless you thought they might be of use - but they'd serve as decorative bullet points in gaming literature, or as a handy indication in your text which die you intend to be rolled, as just two quick examples off the top of my head.
A delightful and thorough piece of either wildly useful or completely useless code, depending on your needs. Fun to play with, though!