Open-source, free, multi-platform BASIC compiler, with syntax similar MS-QuickBASIC (including the GFX statements), that adds new features such as pointers, unsigned data types, inline assembly, a pre-processor and many others.
Vilegust - named for the codesmells that eventually come of such projects - is a basic-like interpreter/compiler project in vb.net that will eventually be self-compilable.
nbasic - bytecode compiler+vm for middle level programming language, like basic. nbs - small and fast C-coded object orientated basic (compiler+vm) for embeded applications. Purpose: scripting support for C/C++ project.