Free and Open Sourced Software that I admire, love, or cannot live without.
In no particular order
Inkscape - Vector drawing program - Like Illustrator
The Gimp - Raster Graphics Program - Like Photoshop
OpenOffice.org - Professional Statndateds based Office Suite - MS Office Compatible
Apache - Web Server
Drupal - Content Management System
VirtualBoxOSE - Virtualization Technoogy - Create and run Virtual Machines on Windows Linux and Mac
Eucalyptus - Enterprise Cloud Computing
EyeOS - Web/Cloud Based Desktop
IPCop - Enterprise/Soho Firewall System
PostgreSQL - Scalable Relational Database System
PostGIS - Add Geospatial Intelligence to PostGereSQL
Geoserver - Publish your Geospatial data online in KML, PDF, Openlayers Maps, WMS, WFS, WCS and more
Mapserver - Deliver powerful web based mapping applications