Free software has been my career for a long time -- nothing else since 1999 -- and it continues to be a happy surprise each time I find a way to continue that streak.
The latest is that I'm being funded for a couple of years to work part-time on git-annex. The funding comes from the DataLad project, which was recently awarded a grant by the National Science Foundation. DataLad folks (at Dartmouth College and at Magdeburg University in Germany) are working on providing easy access to scientific data (particularly neuroimaging). So git-annex will actually be used for science!
I'm being funded for around 30 hours of work each month, to do general work on the git-annex core (not on the webapp or assistant). That includes bugfixes and some improvements that are wanted for DataLad, but are all themselves generally useful. (see issue list)
This is enough to get by on, at least in my current living situation. It would be great if I could find some funding for my other work time -- but it's also wonderful to have the flexibility to spend time on whatever other interesting projects I might want to.