All raw veggies like carrots and celery have good hard crunch appeal. I think a hard apple is a great snack. It has almost become my mid afternoon staple.
As for ice cream, since I have been visiting my Dad I noticed that he has some very small plastic cups that he had been using for his daily ice cream fix.(He had a stroke in 1999 and he has to significantly reduce his beloved ice cream he had every day--he was a four-five big scooper) These cups are the equivalent of 4 spoonsful. Just enough to get that cold creamy taste without a lot of calories, fat, sugar, etc. Works for him and it works for me!