Since I am located on a small campus where there are less then 1,500 students, I am not sure if these ideas will work for you too. But these are some of the things that the fraternities & sororities do for fund raisers at Kettering.
One of the fraternities auctions off their members, the winners of the auction usually make the member they won clean, cook dinner, dress up in dresses for pictures, etc. I know this one goes over well for them but I don't know if it would work at a large school because you don't necessarily know the people that won the auction whereas we know pretty much everyone.
Root beer float sale. One of the sororites does this for a few days during the term right outside the cafeteria. I know they make a decent amount of money. (If from no-one else, they at least make a lot of my money

)
Car washes are also a great idea!!
We did a breakfast sale one term too. It didn't work out too well for us, but that's because engineers don't usually eat breakfast. We sold things like poptarts, fresh donuts, bananas (our best seller), bagels, and the like. One of the other things is, we didn't look into this because we weren't really thinking about it. But we are an organization and I know in high school, the grocery stores used to donate food items, all we had to do was write them a letter asking for what we wanted on school stationary and they would donate for it.
The raffles are also a great idea, i know that there's quite a lot of things you can raffle off. Everything from baskets to gag prizes.
Also, one thing to note: I don't know if you guys have a favorite local charity or philanthropy that you donate to, but I know for us, it always makes us work harder and people are usually more willing to give when a portion of the proceeds go to a local (or well-known) charity that you can explain the goals for to the people.
Hope these help when it comes down to crunch time and the budget's overdrawn! (I know that's really the only time that we start thinking about fundraisers)
Krista
Beta Sigma Phi
Phi Delta Nu