It's a familiar problem in a band or singing group: A song might be easy enough, but the high or low parts are out of a vocalist's range. This simple piece of software helps transpose a song's chords into a different key, so this problem can be avoided.
Rather than working with actual sheet music, it functions with text files, such as lyrics sheets with chords written under them. The program recognizes these chord notations, and transposes them into a consistent new key. The interface isn't particularly elegant, but it's simple to understand once you've played with it for a few minutes. Aimed at musicians who aren't in the habit of sight-reading music, this program certainly may help bring some awkward groups into tune.