Hi Everyone! Great thread--and I think making a symbol is a great idea.
Here is something I thought of that might fit. It may be a bit geeky, but when you think about it, neurons (or nerve cells) are the basis of our love of tickling as it is our sense of touch that is being stimulated whenever we tickle or are tickled. Neurons look a bit like trees to me, and I thought that an artistic rendering of a neuron-like tree would serve two purposes: first as a symbol of the sense of touch, and second as a symbol of the tickling community, which is ever-growing and flourishing, like a tree.
I lack the artistic ability to create what I am describing, but here are a couple of pics of neurons I found on a quick googling. What do you all think?