For PDF: Use your FTP client to create a new folder on your iPhone in /var/mobile/Media/. Name it PDF and drag your PDF files into it. Some of them have to be renamed to meet the usual URL naming conventions. This means: no spaces, no umlauts, etc. I dragged a file named regex.pdf in there. Now I only have to type in the following URL in Safari on the iPhone:
file:///var/mobile/Media/PDF/regex.pdf Safari can display PDF, Word, Excel, and any HTML file you put in the Media folder (...

