I'm a bit behind in covering this site, but it's such a great idea I wanted to mention it. PDFmyURL allows you to almost instantly create a PDF from any page on the Internet. Just type in the URL of any web page, click the button, and wham! Instant PDF of that page. There are also some advanced options that allow you to format the style of the PDF - landscape orientation, header/footer, table of contents, margins, page size, and more.
One thing I really like about this tool, and one thing I'm not wild about:
-- PDFmyURL provides a bit of code that allows you to use the tool on your own website. Just insert the code into any page on your website, and a link reading "download this page as PDF" will be created. It's a great way to provide this functionality to your readers without going to a lot of trouble.
-- On the down side, I can't see where PDFmyURL can create a PDF of an entire website. True, this can lead to extremely large, broken PDF files, but I think a PDF'd website can be very useful. If you need to create a PDF of a whole site, I'd recommend using Acrobat.