This thread is for helping people find books they might have difficulty obtaining. Please post any resources not listed here in the comments, and I'll edit this entry accordingly. (Note: Legal resources, only, please. I'll have to delete anything that points to pirate book sites and the like.)
First of all, if the book is in the public domain, there's a good chance you can find it online at
Project Gutenberg.
Many free audiobooks are available at
LibriVox.
PaperBack Swap and
BookMooch can be helpful, and they do have members outside the U.S. (and some people are willing to send books to other countries).
Goodreads also has book-swapping services.
Read It Swap It is a similar UK-based site.
WorldCat allows interlibrary loans world-wide.
Lastly, if you can't obtain your assigned book where you're at, post here and see if anyone else might perchance have a copy they'd be willing to send you. (Please handle such arrangements via private messages.)