Clipper/XBase compatible compiler with initial support other xBase dialects. Multitasking, OOP,SIX/Comix, SQL and ODBC drivers,a C-API for third-party developers, a few wrappers for popular libraries (such as BZIP, GZIP, GD, Crypto, and Fcgi), ....
A database system, another, older database system, a compression library, something to do with menus and XML, and whatever I happen to be working on at the time.