Car washes? When I was a kid we wen't around getting "pledges" for cleaning up a section of the business area of town. We took our pledge sheets out for a week or 2 and went to each of the businesses in the area and friends and neighbors and what have you asking for donations or pledges for numbers of hours worked up to a certain number of hours (we were kids, weren't really allowed to just go on forever). Then on the promised day we took our little trash bags and gloves and picked up all the garbage around the area. Then your adult group leader filled out how long you stayed and worked and you went around collecting your pledges. We made quite a bit. Businesses and even patrons of the businesses were happy to donate. Most of them didn't even actually pledge they just handed over cash so we didn't even have to go back and collect. There's no overhead except for trash bags and gloves and it helps the environment and makes your town look better while making quite a bit of money.