During my first week I worked on an application called abba—the abbreviation engine.
abba began life as an adaptation of the New Abbreviations, the shorthand system that I've been working on since 2006. I wanted to write an application that could basically model the the Abbreviations—the challenge being that many of the abbreviations I made up have no unicode equivalents, and so you couldn't simply write a script to do unicode character replacement.
Instead what abba does is insert references to abbreviation objects, which exist independently of their representation in any given medium. It does this by the rather clever method—originally suggested by Tom, I think—of passing through single high-plane unicode characters which can then be dereferenced at rendering time.