Hanging upside down from your legs ..
And hanging by your arms ...
Apart from that skipping ..
There is a LOT of Yoga too... I have a detailed study which was carried out. If anyone is interested PM me.
Eating nutritious food.
I actually believe this because I studied kinesiology in college and as long as the cartilage and epiphyseal plates on your knees haven't closed, stretching can actually make you taller...but do avoid lifting heavy objects...that's why a lot of weightlifters are really short...
We also had a case study in college about a 32 year old man who was 5'6 last year but have grown to 6'3 because he got hit by a falling tree branch and his anterior pituitary glands got affected somehow and he started producing a lot of GH...
oh, and for those who are thinking about hitting their head, please Don't...