Firstly I own The Red Theory, an online agency specializing in custom web applications and online marketing.
We build mostly with PHP/MySQL and deal exclusively with open source technologies.
I have also created / run the following:
Hexna.me - Webapp to help remember your colors as you code.
Delim.co - Online comma separation tool
Vodkarocks.com - All things Vodka! Taste tests/etc.
Yardgaming.com - Descriptions of various yard games.