Nettle stings sensitise the skin, thereafter even the lightest touch send shock waves through the affected area, an interesting feeling. Yeah and nettles are useful, they can be eaten like spinach, and the boiled out sting makes good shampoo. Nettles have also been used as a dye for military camo netting and the nettle fibre is very strong and has it's own uses.
Oh and for those of you that suffer cold legs, do what the Romans did, brush the things over the skin, the sting is great for warming cold legs. Sensitisation of skin by stinging increases blood circulation and therefore warming, so people next time you get stung by nettles, let it serve to remind you, you have been made aware of such a useful plant, celebrate it's glory and stop being a big wuss.
Oh yes, nettle beer ain't too bad either, loads of iron content.