CalcG.org is a redesign of a website that I created in high school (CalcGames.org, which features the same content with the old layout). It contains an archive of games and programs for Texas Instruments calculators, a news section, and a fully functioning forum. Virtually all parts of the site were created from scratch in Perl and PHP with a MySQL database. There are over 30,000 registered users, and have been millions of visitors (accounts are only required for the forum and to rate files).
In addition to creating this website, I was also very interested in programming for TI calculators in high school (specifically the TI-89). I created several somewhat popular games for it in C, the most popular of which is Tankers (which even features a multi-player mode across a link cable between two calculators).