Start an air conditioner repair company. You can take a 2 yr course, do a couple jobs, buy a big ass van and hire a crew to do all of your work for you. 100bucks min per visit and you'll have around 6-7 visits a day.
Something that is always needed is the best option. But then again...
If you could get your hands on some nice property. The storage idea has been the easiest money maker I've seen yet.