See Deviant Art Original Link Here.
The artist's name is Calisto-Lynn.
As I am a 'huge' Mass Effect fan, I don't think I have to argue why Tali's romance option is so popular.
- Her face is a complete mystery. She can look like anyone.
It is not clear whether or not Bioware will reveal Tali's real face to the audience, but as I was perusing Deviant for Mass Effect art I came across this.
This is a pretty sweet image of what the mysterious Quarian 'might' look like.
VictorNiss
This is a remade version of a piece of concept art floating around. Apparently a man (Claiming) to be a conceptual artist that had worked for Bioware posted it, and stated that "This is Tali's face- that is all I'm going to say..." after his discovery (and disappointment) that they never show her face in the 3rd game. My buddy knows the original artist's name, I'll bump it once he responds.