Links...

Harbour related links

Harbour at SourceForge
Andi Jahja's Harbour binaries
David G. Holm's Harbour binaries
Installing and porting to Harbour, An article from David Mertz, Ph

Free compilers and Lex/Yacc tools

Apple MPW tools
Cygwin
Cygwin Resources on the Internet
DJGPP - a complete 32-bit C/C++ development system for Intel 80386 (and higher) PCs running DOS
Mingw

A Guide to Lex & Yacc
BISON, a GNU parser generator
Compiler Construction using Flex and Bison
Introduction to CVS by Jim Blandy

GNU links

GNU (Gnu's Not Unix)
Yahoo's links to GNU
GNU make

Free Chat Clients applications:

Microsoft's MSchat 2.5
mIRC