Alaska Xbase++ - A 32Bit compiler for the Clipper/Xbase language on the Windows platform. - http://www.alaska-software.com/
Harbour project - A public project for an open source Clipper language compatible compiler. It will become a 100% Clipper compatible compiler for multiple platforms and includes all source code - http://www.harbour-project.org/
FlagShip - A database development and porting system for moving xBase based languages to UNIX. - http://fship.com/