If you haven't heard yet about them, I suggest you take a look at the 5M-model and Edward's SHEL model.
HFACS (Human Factors Analysis and Classification System) is supposed to be quite good. There's a book by Douglas Wiegman that sees a lot of use in my company.
Also, Sidney Dekker's Field Guide to Understanding Human Error might be a good starting point.
I hope it helps :-)