We have done all sorts of things.
Auction-each teen would offer themselves up with a specific task in mind, lawn mowing, laundry, car washing, babysitting, etc, and then members would place their bids. You have to make sure that the kids actually provide their services though.
Food-all sorts of things here, bake sales, dinners, breakfast, you can do gift food jars, put all of the dry ingredients into a glass jar or plastic baggie, decorate it nicely, include the recipe and then sell it. This is especially nice around the holidays.
Local small business owners-find some local people that make things, such as candles, etc. We have a friend that does this and they are sold for very reasonable prices and the groups make 50%. I did this also in high school with our choir, a local goats milk farmer made soap, we sold them, an extremely nice product, and got a 50% profit.
Area resturants-many, many resturants will do a church night, or several days a month. if the church member mentions their congregation, they donate 20% of sales to the church.
Car wash in conjunction with some sort of food sale-in our experience this is a great way to get parents and other members involved as well. Have various foods available for purchase while their car is being washed.
Frozen dinner sale-have a couple of really good and generally liked recipes that can be frozen, main dish and sides would be great. Spend a day assembling them in aluminum trays (try to find the ones that come with an aluminum topper, you can write instructions and names on the top easily). Then you deliver them to those that ordered the meals. They can cook them that day or save it for later.