Try these:
pack your lunch for work and save the money from eating out
save all of your loose change at the end of each day
When you write a check, round it up in your checkbook (similar thought to saving change).
Every time the kids/you want to eat out or get "just one thing" - don't. Take that money and add it to the WDW fund.
Buy Disney Dollars each payday (NOTE: Policy on returning unused Disney Dollars has changed and now requires the receipt so don't overbuy Disney Dollars).
Give the kids their allowance in Disney Dollars.
Tell everyone that you are going to WDW and would like Disney Dollars for birthdays and Christmas gifts.
Use coupons. Take the amount of money you saved and it to the Disney fund. Check out
www.mycoupons.com for lots of couponing info
Join rewards programs---check out the rewards forum on this site for more information.
How about a part time job? Nothing strenuous, just for fun. Weekends only maybe?
Make it part of a "big gift". For everyone's birthday/Christmas/etc. you are getting a park pass.