My largest tip was 100%, to a waitress I had known for a long time. It was meant as a wedding gift. It totaled about thirty dollars, but I didn't have much at the time either.
My smallest tip was $.01, to a waitress that seated us at a very wet table. Then didn't dry it. Then waited over 30 minutes to take our order. Then had the audacity to ask us how we wanted to tip her. There were only four other tables occupied in the restaraunt, and she was talking on the phone. I figured if I left nothing, I was just a jerk. If I left a penny, she would have to figure out why.