Andreas Gohr has posted a guide for creating a mobile Apache installation that could run on something like a USB stick.

Today I spent some time to figure out how to compile a relocatable Apache with PHP support. Yes, this might result in a Linux version of the DokuWiki on a Stick project. Read on for detailed instructions.

The installation is pretty similar to the normal compile with a few small differences. Check out the post for the complete process, commands and all.

PortableWebAp is a portable platform for web applications. With it you can run php web applications from a CDROM, DVD, USB Drive, from any directory from any hard drive. No installation is necessary.

It'll only run on Windows 98 or higher machines, but it has everything you need right there in one, handy package. It (currently) comes installed with PHP 5.1, SQLite 3.x, PDO, and the PHP command-line version - all in about 5MB. Once it's running, it can drop down to the system tray for a less intrusive execution. And, by default, it runs on port 800 so as not to interfere with anything already working on the standard port 80. And, of course, it's pretty cheap - a small price for a lot of time saved.

You can check out the project here...