Get a Family Membership to Milwaukee's Discovery World for 1/2 Price. A membership is normally $75. That means you can receive it for $37.50!
The membership includes free, unlimited admission for 2 adults and 2 children or grandchildren under the age of 18. (Children under 3 are always free.)
The sale begins on July 3 at noon at THIS LINK. Hurry because they are only allowing 73 memberships at this price. (I have a feeling they will probably go fast, so I am going to get mine right at noon.)
Tickets for adults are normally $16.95 per visit, so if your family goes one time in a year... you've paid off the membership. Plus, this membership gets you into 300 other museums in the country, including museums in Chicago and the Children's Museum in Madison and The Building for Kids in Appleton.
Thanks to Julie for the tip!