Blind Taste Test
Use small bowls and tasting spoons to create tastes of various cookie ingredients, calculating two types of ingredients for each guest. One at a time, blindfold guests and have them taste an ingredient, trying to identify it by taste alone. Each guest tastes a different ingredient so that everyone can both participate and spectate. Those who answer correctly move on to another round; those who are incorrect become permanent spectators. The elimination continues in this manner until one person remains and is the winner. If you go through all of the ingredients, you can repeat them, but be sure not to duplicate tastes with any one guest.
Cookie Contests
Ask guests to tell you what kind of cookie they plan to bring as part of the RSVP. Prepare a name card for each cookie type as well as a voting card for each guest. The cards should have the name of each cookie in a column down the left side and contest categories across the top. Some common categories include best presentation, gooiest, fewest ingredients, and most unique ingredient. Each guest becomes a judge and when all the votes are in, tally the results. Make a big production about revealing the winner in each category. Consider listing the top three, with a drum-roll for the winner or an Oscar-style envelope revelation. Winners can receive a small trophy or other prize.
Cookie Memory
In addition to cookies for the swap, ask guests to bring enough cookies for each person to have one at the party. Once everyone has arrived, have each guest introduce herself to the group, including among other things her name and what kind of cookie she brought. While guests are mingling and getting to know each other, make a numbered plate for each type of cookie. For example, plate number one is Shelly's oatmeal cookies, plate number two is Lisa's chocolate chip cookies and so on. Hand each guest a paper numbered to match the number of cookie plates. Guests then taste one cookie from each plate and identify as many as possible, as well as the person who brought them, by writing their answers next to the corresponding number on the paper. The guest with the most correct answers wins a small prize.