Sometimes it's annoying to have to use Mail on my iPhone to review a PDF, Word or Excel file I received a couple of days before. I wanted to have permanent access to some of my inportant files (roadmaps, notes, lists etc.) even when I can't go online. All you need is a jailbroken 1.1.3 (or newer) iPhone, an FTP client on your Mac, and the "Safari 1.1.3 Patch" for your iPhone (see the Big Boss' repository: "Adds file:// support for local files viewing to Safari.")

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 (or in a sub-folder of Media). Additionally, you can save this to your home screen, or as a bookmark, for easy access.

Additional hint: instead of typing the URL in Safari on the iPhone, you can do that on Safari on your Mac and save it as a bookmark for later syncing to the iPhone.