Music in the caf is something that has worked well at my school. It's a very simple way to raise money for any events (united way, cancer, etc) Just have a stereo brought to the cafeteria during lunch time and have your org. (i.e. student council) bring in all their c.d.'s and charge the students 50 cents (or whatever) to hear their favourite song.
You can also add a twist with the VETO rule. If someone doesn't like the song that is on, they can pay 1.00 to have it turned off. Then 50 cents for the song they want to hear. It works well and the kids love to have the change in their lunch hour, which we all know can get pretty boring!