Alisa Kiss is an awesomely cool cosplayer. While I think her Supergirl is one of her best, she still does a kick-ass Sonja.
Here she is, with some inspired art.
Red Sonja 6 by *AlisaKiss on deviantART
Red Sonja by ~Diewtiful on deviantART
I am going to have to do a series of her pics one day!