In my troop, we found that the fundraisers work best when the ideas originate with the scouts. Last year, the PLC and Troop Committee felt that it would be beneficial for the troop ton try to subsidize some of the summer camp fee - we wanted to have a coach bus transport the troop to camp. The troop's main fundraiser had been popcorn sales, which the scouts have never really gotten into, but it generates enough to keep the council happy and cover most of the troop's operating expenses. The troop also does a few other fundraisers periodically, with most of the proceeds going into the scouts' individual accounts.
So, the PLC was charged with coming up with a fundraiser that the scouts in the troop would commit to. At the PLC meeting, several ideas were discussed, and several were discarded. The one that had the most support and seemed to be the most feasible was the idea of running a dunk tank at our town's weekend fair. The SM was skeptical that the scouts would actually want to follow through with this, so suggested that the PL's go back to their patrols and gauge support and commitment. The report was that the scouts thought this was a great idea, and would run with it. So, the committee set up reserving a spot at the fair, and renting a dunk tank - and that was the extent of direct adult involvement!
The PLC came up with a great plan to assign each patrol to a 2-hour slot for working the tank. The duties would rotate - one patrol member would be on the "hot seat", one or two would handle collecting money and the balls for the target, and the rest were responsible for "advertisement" - trying to get as many people to pay the $1 for three chances. The patrols made signs, costumes, cheers, etc to use for their advertising. Whichever patrol made the most money would win a pizza party, which a couple of the adults agreed to pay for. To sweeten the pot, if the troop was able to raise enough to cover the cost of the bus, the SPL and ASPL would volunteer to get dunked in their full uniforms (the scouts, by the way, wore their troop T-Shirts and jeans or shorts when working this).
The event was incredibly successful, and we're planning on doing it next year. We raised about $1100 (more than enough for the bus) - not bad for two days! The scouts really had a blast with the competition thing, and there were no problems with getting enough scouts to work each shift. Also, there were just a few scouts who didn't want to go in the dunk tank, but were able to participate by collecting money or other "dry" activities. The circumstances were also working in our favor - we had excellent weather, and the fair was very busy - a good chunk of the money we earned came from friends the scouts had from school or church, or from the scouts (and their families) dunking one another.
What's even better about this is that adult involvement was a minimum - the committee handled renting the tank, collecting permission slips for all the scouts (we thought it would be a good idea if they would be in a dunk tank), and adults rotated supervising the scouts in the tank. Believe it or not, the fundraiser also help boost patrol unity - an all-around benefit, and the scouts are already talking about it for this summer.