We do many of the same program listed in other responses (GM Box Tops, Safeway escrip, Albertsons Community Programs, etc.) and they are great.
We also do a monthly "School Night Out" at a different location each month. Chuck E Cheese has been a favorite, because they give a sticker reminder for each student to receive 10 free tokens when they come... they don't even have to pay for anything... yet those families who do purchase food, tokens or other things from the counter, we get 15%... it is a fun time and we make about $300 for one evening. Other successful locations have been Sweet Tomatoes, Pick UP Stix, Rubio's, Chevy's... In-N-Out Burger even brought their trailer to our school!
As for fundraisers, we have done many different catalogs (we do a catalog sale in the Fall). Our classrooms raise money with jog-a-thons, math-a-thons, etc.
At the end of the year a big fundraiser is a silent auction during our final social event (2 weeks before school ends). About in a month in advance,we request each classroom to put together a themed basket for the auction. One parent per classroom is responsible for collecting items and donations for that basket. The class with the highest percentage of participation (does not matter value) receives a reward... one year every single classroom donated a basket (don't expect 100% participation) so we rewarded the entire school with frozen Otter Pops (hot day). In addition to auctioning the baskets, we collect donations from local businesses. Sometimes we add these to the baskets to increase value/desire and other times we auction them off independently. We have received tickets to local entertainment (bowling, movies, amusement park, museum, etc.), items (sunglasses, health club membership, toys), and meals (In-N-Out sends meal coupons and t-shirts, Elephant Bar, etc.). Since all the stuff for the auction is donated, all the proceed (minus rewards like Otter Pops) is profit... we do use one of the donated items to reward the most creative basket... like when a company sends 20 meal tickets or something like that which can be shared by a class.
Communication and consistency seem to be key in having a successful fundraising event. Good luck!