Just yesterday I bought US$100 worths of books from Amazon which cost me an additional $50 shipping to Australia. I'm never quite sure whether I'm still getting a great deal after the shipping charges are included but I really can't be bothered manually checking umpteen different stores local and overseas to find out where I can find the cheapest price for each of the 7 books I ordered, taking into account the combined postage if dealing with multiple book stores.
Enter AddAll. I just discovered this site and as a book nerd its bloody awesome. The key features that make this site rock are 1. it takes into account your destination country which is important to take into account postage costs, and 2. it'll search for multiple books and return you the best overall package. Holy crap, its like someone finally made computers do what they're good at - crunch lots of combinations - to save us poor human beans time and money (literally! :).
There were no ads that I could see and according to the FAQ AddAll makes its money through affiliate commissions - that's perfectly fine by me.
I'm doubly glad that someone's already done this because if they hadn't I was about to spend months of my life hacking something up. Big thumbs up.