Making a Living Building Open Source Software?

asimbaig asks: "When I started my IT Staffing and Placement firm last year, I couldn't find a decent Applicant Tracking System (ATS) or an Open Source alternative. I then found SugarCRM, and was blown away by its power and ease of use. Partly frustrated with the existing vendors and partly inspired by SugarCRM, I decided to write that ATS using LAMP. 6 months and 45k lines of code later, I have just released the preview of industry's first Open Source ATS/HR Management system, called CATS. Now, it will be an interesting experiment to see if I can actually make a living out of it and move away from my IT staffing business. SugarCRM seems to be doing well, so why not?. Is anyone out there making a living from writing Open Source code?"