Spring tune-ups would be simple enough...blade sharpening, oil change, new plug and a power washing-$45.00??? for 21 inch mowers.........2 cycle stuff needs cleaning and gas filter replacements, grease the heads.
People who know that I have a repair shop set up for my business equipment come around and expect freebies.
I hung a sign up that says "Shop Fees are $ 38.00 per hour, plus parts."
My point being, why not advertise on Craig's list for free and do some work out of your own shop? It'll be busier in the spring though.