I just got done doing a jewelry fundraiser for a school, they raised over 3K! And it was with minimal effort for them, I did most of the work. All they had do do was "hand out" the orders.
For the time and effort involved, we got the most return on Krispy Kreme donuts and Marble Slab Creamery Cakes. All we did was copy the order form from the Krispy Kreme site, set up our account with our local store, put an information label on an envelope so students have a collection envelope and collect it back. When the donuts were delivered (which was 10 cents extra per box and a VERY WORTHWHILE investment), we let our parents come pick them up.
We did a phone call to our order takers on the night before to let them know to come by and get their orders, along with announcements during the morning and afternoon before the pick up.
Netted almost $3000 for little to no work.
It was the same with Marble Slab Creamery Cakes, but they printed the order forms in color for us. We netted $2000 on that one.
During the summer, we are hooking up with all kinds of restaurants for fundraisers. Our new board is purchasing or making a billboard that can be pulled around and set up ahead of time to advertise for us.
Everybody will be eating out over the summer, so there's no reason not to fundraise during that time.