Tangentially, I'd also like to point out the article Torsors Made Easy by John Baez. OK, to be honest, I'm not sure how understandable this really is to someone who doesn't already know a bit.

Having read that article years ago, without any previous exposure to the concept of torsors (other than the implicit exposures Baez notes, that everyone's had), torsors also came to mind for me when reading nyan_sandwich's article.