I am the world's biggest bore on fund-raising, I just love it (but get a bit depressed as few of my friends seem to share my opinion!!) - I do fund-raising for playgroup & charities, not yet school, but these are some of the things we have tried, with varying success!
Cake sales, table top sales, jumble, car boots,lunches, quiz evenings, fashion show, cheese & wine, auction of promises, coffee mornings, 80/20 sales (clothes/toys etc), book sales, discos, race night, tombola - don't forget that sometimes a 'direct appeal for donations' can work well if people can't be bothered to support you, they may prefer to send a few quid.
IMO it is important to try and target different people who will spend money, ie: do not automatically assume that all the school parents will support you.
For schools I think that those printed tea-towels (with children's handprints) sell well - parents will buy them for Christmas presents etc.
I also think you need a specific target to let people know what you are raising funds for ie: we need £250 for library books or whatever.
Good luck - what are your ideas ?