soy
I've got the allergy thing going (why I couldn't have figured out that I couldn't breath all through childhood because of milk is beyond me) and second the soy suggestion. Silk is my favorite soy milk, but I like the plain best. The vanilla is very sweet, but it makes great smoothies. The chocolate is nice as a treat. Westsoy, Edensoy and Pacific make pretty good soy milk, too.
If you see soy yogurt, though, run! Well, sort of. The plain works okay in recipes, but the flavored stuff does NOT taste like yogurt. As time goes on, though, I'm forgetting what yogurt really tasted like anyway, so I can handle the stuff better. It's really sour, though.