Inspired by a recent posting on MacOSXHints.com, I've been using PrintFu.org to print out copies of my book manuscript for the various readers that are reviewing it. My book (on deaf politics and sign language in modern Japan) is about 300 pages long. PrintFu can print it for about $11 with postage in the USA.
PrintFu isn't perfect. They initially had some problems with the fonts in the book. And the printing itself is OK, but not super-fancy. It's perfect for draft manuscripts and other large printing orders (i.e., documents with hundreds of pages), but don't use it for your wedding announcements. But they're cheap, convenient, friendly, very helpful, and fast. You can't beat that.
2005.04.02: I was having trouble collating the various chapters of my book into a single PDF to upload to PrintFu. Microsoft Word insisted on producing multiple PDFs for each section/chapter , but Brandon@PrintFu suggested a toolkit called pdftk that did a great job of concatenating them. It's a unix tool and a bit user-unfriendly, but it does the trick if you don't own the full version of Adobe Acrobat.
Don't for get... Helpful, too!