Gift buyers search Etsy for things like "speech therapist gift," and most of what comes up is generic. A former college administrator in Florida designs joke mugs and candles for specific jobs, lets a printing company make and ship each one, and sold more than $560,000 in about two years. She started with under $40

Everybody has a garage pile they want gone, and nobody wants to haul it to the dump. Junk haulers charge by how full the truck gets, and one California operator who started with a used pickup now averages $549 a job. Apps like Thumbtack are where many of them find their first customers.

Dog owners love their dogs and hate the backyard. A Virginia couple started scooping yards before and after their day jobs in 2000, and DoodyCalls now has more than 100 locations. At about $18 a week, 50 regular yards comes to roughly $3,900 a month.