NPR recently ran an article about how playwrights support themselves when not writing. Actors too have to be creative in order to suppliment the little (if any) income they earn from their acting.
Beyond the regular and fulfilling acting gigs, actors often participate in educational theatre and children's tours. And of course there are always teaching gigs for those crafty enough to get them.
There are the standard industrials such as commercials, voice overs, and industry shows.
There are always the corporate trainings where companies with surpluses of money call actors in to play improv games with their staffs to improve workplace productivity.
There is always extra work in movies.
And if all else fails there are the day jobs, temp jobs, and wait staff gigs as well.
What are some of the other jobs that you've heard of to help sustain actors in their pursuit of happiness?