These are rough notes from Richard Borcherds' quantum field theory seminar from spring 2004. They are probably riddled with errors, and Borcherds has informed me that many of the ideas are out of date. In particular, he has changed his mind about the definition of a quantum field theory a few times since then (making it shorter each time - I think it's down to four or five words as of spring 2007).
Here is the course web page and a list.
From the fall 2001 course: notes by Alex Barnard, a recommended preprint, and the take home final. I have notes of my own, but the principal difference between the two versions is that I wrote down more jokes and slanderous remarks.
Notes from the IAS QFT program: fall 1996, spring 1997, UCSB 1998, UCSB 1999.