Everyone loves a bargain and mothers are no different. I've always wanted to create a membership site that showed people not only how to save money on everything from groceries and fuel, but to be able to offer discounts to products from the membership site.
Sort of like an online coupon, but instead you pay a flat monthly fee and become a member of a membership site, with articles, forums, etc.... and you get discounts on selected products.
I think this is a real winner of an idea.