It was initially an extension of a relationship I had while in academia. Several regular employment stints came afterwards, just from talking to people.
There are a few contract engagements I don't put on my resume: adding stuff to a few WordPress sites for friends; setting up a small Beowulf Linux cluster; debugging a Microsoft Access application for a small business. The main reason I don't list those (and a few others) is that I don't want to do them ever again. The secondary reason is that I don't want a full-time employer to know that I am/was working on the side.
More recently, a old classmate from grad school - with whom I worked recently - recalled that I was/am a specialist at running and interpreting the results of a clunky piece of software.
Presently I am not working and am starting a contract as a GIS data scientist for a telecom company in January. That one I got from a recruiter who needed someone with my skill set.
Note I have updated my contact information on my HN profile, from which you can infer what my LinkedIn profile is and have a look.
