Wow! These are all such great ideas! I shop at Children's Orchard almost exclusively for all of my son's clothes and I trade in the ones he has outgrown. They take toys and videos and furniture too! I picked up a double stroller for my in-laws for less than $60.00. I also get an email from them if they have specials like, all the clothes that you can stuff in bag for $5.00.
I also sell things on Ebay and Craigslist that I know I can get money for and don't want to donate. This is a tidy little way to make a profit. That way if I want to buy something, I usually carry a balance over from my Paypal account from things I have sold and I don't need to "spend" anything.
I use my Entertainment book like a bible. I also take advantage of the parks and recs in my town for classes and activities that are free or cheap. The public library has a ton of free things for kids on the weekend. I also get all my books and videos there.
And lastly. Pimp out those husbands! I do this routinely! If your sig other has a skill, or trade, see if you can barter that for something else. My husband helped Heather's husband with something (I cannot recall what now) and her husband came later and painted my whole house! What a savings that was!