The photo is a reconstruction from Nicholas' skull, made by a forensic anthropologist. Nicholas was briefly disinterred in the 50s, and high-quality photographs of his remains were eventually used to create a 3-D image of his face. Nicholas was Greek, so his complexion is a little more olive than the rosiness of modern Santa Claus.
Nicholas had a broken nose, which may be related to accounts that he was imprisoned and tortured during Diocletian's persecution of Christians in AD 303. Like most other bishops of his time, he was present at the Nicene Council.
There are all sorts of interesting stories about St. Nicholas: he gave dowries to poor girls to save them from prostitution; he appealed on behalf of unjustly condemned men; and my personal favorite: he slapped the heretic Arius in the face at the Nicene Council.
Of course, you should probably take all of this with at least a little grain of salt, since legends tend to accumulate around saints and their remains - but I think I like Nicholas of Myra better than the fat man at the North Pole!
As good old St. Nick would say, Kala Christougenna!