Our PTA had huge success last year selling coupon books geared to our town. The company that makes the Entertainment brand coupon books provides these but they are not the massive, thick Entertainment books you may know -- these are small folders with maybe 20 coupons plus options to get online coupons -- all local businesses, restaurants, hair places, free entry to the local rec center, etc. I buy a couple just for us, they are so useful.
Another option is selling "scrip" -- gift cards to businesses. For instance, you buy a $100 card for Safeway and use it, spending all $100, but the school gets X percent. Our dance school sells scrip cards for fundraising and did very well with it last year too.
These things are both much preferable, to me, to mere stuff like wrapping paper, hand cream, candy, and other junk. They certainly are not the $1.00 items others mentioned but are $20 for the coupon books and anywhere from $10 to $100 for the scrip cards, but they are far more useful.
You can sell scrip cardsto folks if they realize that they're going to buy groceries or gasoline or go to Starbucks anyway, so why not pay when they're at those places using a card that got the school anywhere from 3 percent to 12 percent of its face value? Also, I know a lot of families buy heaps of the cards as Christmas gifts for family, the piano or karate teacher, the classroom teacher, the lawn guy, whoever gets a little remembrance at the holidays.