Project Euler/17
From charlesreid1
Problem 17 deals with the number of letters it takes to spell out a number.
First, let it be said that this is a problem that shows how tremendously awful language rules can be, when contrasted with the happy certainty of mathematics.
This basically requires about 20 special cases, and from there things are relatively smooth. This program only goes up to 1,000, but it would be entirely plausible to extend this program to go even further.