- Linux - open source operating system
- Apache - open source web server
- mySQL - open source SQL data store
- Perl - most craigslist software is written in Perl (tmtowtdi)
- Sphinx - open source search engine
- OpenStreetMap - geographic data for the world
- Haraka and Postfix - email servers
- Redis - open source key-value store
- MongoDB - open source NoSQL database
- Git - open source version control
- GNU - emacs, gcc, bash, the concept of free software
- Mozilla - Firefox, bugzilla, etc
- Pine - email client, "it works"
- Wikipedia - the world's encyclopedia, "we link to thee"
- EFF - watching over our rights in the electronic world
- WELL - online community pioneer