Tables in Wonderland is a dining discount program for FL residents and AP holders (and DVC members, too, I believe.) It costs between $75 and $100 and gives you 20 percent off food and beverage at most WDW table service locations, and a few QS locations. You can use the discount for up to 10 guests in your party. At TS locations they automatically charge an 18% gratuity if you use a TiW card.
Because we are FL resident AP holders and opt for room discounts instead of free dining promotions, the TiW card is a great way for us to save on meals.