Best of Breed

In my humble opinion these are the best Open Source projects. This is not an exhaustive list. There are many fine open source projects. But these are top-of-mind for me.

WordPressBest Content Management System
ApacheBest web server
PostgresqlBest database
FirefoxBest Internet browser
Debian LinuxBest O/S distribution
GCCBest compiler toolset
Click on left column entry to find writeup.