Why installing Apache-PHP-Mysql on an USB flash drive ?

I’m a lucky guy. I own several Macs, at home, office and a MacBook (see here). I am developping teepsy and I was looking for an easy solution that would let me install Apache, PHP and MySQL, and my scripts, on various computers, and which allows me to continue my work on my scripts, without thinking about the machine’s config.

I was looking for a solution like WAMP, under Windows, which contains all that is necessary for a PHP developer : a server (Apache), PHP and MySQL. On Macs, this solution is called MAMP.