If you haven't seen it, there's a whole board on ways to save at Disney, under budget board.
Outside of that, some of the strategies are to plan days at the park and some days when you just do the resorts (pools, rent a movie in the room, have dinner at another hotel and walk around). My DH, DS and I spent a whole day looking at Downtown Disney and the other areas near by. It was very relaxing and lots of things for toddlers to touch and play with, even some sandlot/playground space.
Another good tactic is to have your big meal at lunch time, around 1 or 2pm and take advantage of the lunch time prices. You can see all the fun resteraunts and save a little on the price, then have counter service for dinner.
If you have a lot of people going, it is great to get the one-bedrooms (or more) with the kitchens. Then you can grab breakfast in the room and pack snacks for the day for younger kids, and not have to buy everything in the park.
I'm sure there are many more ideas on the budget boards, but be sure to read the advice about discounts and the seasons for buying rooms. It will make a big difference in costs.
Good Luck!