I make it a habit to visit the MIT Press whenever in Boston. Granted, they don't have a loading dock sale every day, but they may well have a few racks of similarly-discounted clearance books.
Just got back from the sale... got about 80 bucks worth of books (lots of $100+ books if from amazon). 11 books total, a few books the size of rhode island.
Ah, the loading dock sale. I remember those well. Some of the things I found there in the past included discounted copies of SICP, 'The Little Schemer', and the entire source code of PGP (yeah they put it in a book, don't know why). There was a companion book for the PGP code that I always kept an eye out for, but was never on sale.
There's also a lot of economics/sociology books on sale, so you can pick up esoteric things on a number of subjects. Just go, go, go.
> the entire source code of PGP (yeah they put it in a book, don't know why)
Because PGP used keys larger than 40 bits, which meant if was classified as 'munitions' (!) under US export regulations. Zimmerman got around that by publishing the source code as a book, export of which is protected under the First Amendment. You were supposed to OCR it...
http://ycombinator.com/newsguidelines.html
edit: the title of this article used to be uppercase. either the submitter or an editor has since changed it.