I found a tofu mayonnaise recipe! I haven't tried it yet, but it might be a good solution for anyone who has trouble finding a (palatable) low-fat/fat-free mayonnaise at the store.
Tofu Mayonnaise from _Nikki and David Goldbeck's American Wholefoods Cuisine_
1/2 pound tofu (1 large or 2 small cakes) 2 tablespoons lemon juice or cider vinegar 1/2 teaspoon salt 1/4 teaspoon prepared mustard 3 tablespoons oil 2 to 4 tablespoons water
Pat tofu dry with a paper towel and combine in a blender or a processor fitted with a steel blade with lemon juice, salt, and mustard. Process until creamy. With machine running, add oil through feeder cap, then water, until mayonnaise is of desired consistency. Makes 1 cup.