I know that Pizza Hut does it and I am pretty sure that there are other chains that do it as well. You would have to contact the resturants and dicuss it with them.
We have a Burger King nite. Burger King gives us back a portion of money spent from receipts put into the school drop box at BK. It's not a lot of money but the kids look forward to it. The only real work is setting up the dates, making sure the receipt boxes are at BK before start & get picked up and printing up the flyers.
Do you have a Carrabba's in town or with in 25 miles or so. They do a dinner night for us at our school. It is prepared there and the food is fantastic.
You might also want to look at this old thread on promoting events - sending flyers home, printing stickers and applying to the kids' shirts right before they left, using sandwhich boards.
Sticker/Flyer Discussion
We used to do a lot of these in elementary - Chick-Fil-A, McDonalds, pizza, ice cream shops, etc. Also amusement places like skating, putt-putt golf, etc.
While not huge money makers, we found these to be pretty low effort and a lot of fun. Aside from whatever funds they brought in, it also served to increase school spirit and to have a time for a lot of us to get together to socialize.
You could ask practically any restaurant, independent or chain. All they could do is say "no", and they might well be interested.
Note - my neighborhood is an indepdedent suburb of about 10,000 people, sort of like a town, but without the infrastructure. (Not inside anyone's city limits.) It has a "give-back Wednesday" the 1st (pizza), 2nd (barbeque), and 3rd (Mexican food) Wednesday of each month. It's a standing arrangement with 3 local restaurants. They donate a percent of the proceeds from those specific nights. The money is split between the soccer association, the swim team, and the library. We all know it's a good cause and try to coordinate eating out to support this program. Plus the members of those groups really try to promote it. This one has been in place for about a year.