Thanks for the responses. They ranged from the highly practical to the exotic. I loved the idea of Tzaziki sauce, but not being a fan of cucumbers, I went a different direction. As for hummus, I've only had the hummus you can buy at the grocery store. I imagine the homemade version would be a lot better.
I went with a simple Beau Monde dip recipe (3/4 cups mayo, 3/4 cups sour cream, 1 tbsp minced onion, 1 tsp each of dried parsley, dill, and Beau Monde seasoning).
I also went with cream cheese and Picante sauce, which was great on carrots as well as chips.
We also had a fantastic brandy cheesecake dip that was surprisingly popular with the fruit-eating crowd.