I have one idea for the short summer. I live a mile away from a part of town with something like 8 hotels crammed into a small area not a 1/4 mile long (it's near the airport).
So in the summer, you see hundreds of bored tourists walking around this commercial strip of town, just to get out of their rooms and do something before their tours, flights or whatever the next day.
Thing is, there's a very nice trail just 1.5 miles away that runs along the sea, with nice views and forest. My business idea is just to buy a van or mini van, trailer, couple of bikes, and telephones, and bring tourists out to this really nice trail for a bike ride, then pick them up and bring them back to their hotel at their convenience. Make brochures and plant them all over the hotels, bribe hotel staff for any referrals that result in customers. It'd probably cost $10,000 to start up. Only problem is, the season is just 4 months long.