The scenario
You are on the go all the time but have access to many computers other than your own.  All of your work exists on a combination of USB drives. You have 2 USB drives each one is 16Gigs.  One USB drive for all of your applications and another loaded with all of your hard work.  Your laptop battery is dead or you just want to use the computer that is available to you at your each of your destinations.

Why Am I Into This
I went on two vacations and didn’t take a laptop with me.  I like the idea of having everything I need, in the computer realm, be incredibly easy to access.  While traveling I had 4 devices with me.  My Palm Pre, 2 USB sticks, and my camera.  I have portable version of the software I most often use.  “Portable” means it fits on a USB drive and has been rewritten to work from one file or directory on the drive.

Some Ideas
How great would it be to be able to boot into any operating system?  Live versions of each of the primary 3 exist out there.  Windows MAC osX Linux Linux will run the fastest in most cases.  Don’t be afraid of Linux. The way it places applications on the system is very similar to OS X.  OS X is actually built on top of Linux and that is why they are so much alike. If you run OS X from the USB drive it will likely be the slowest of the 3 for the same reasons mentioned, it’s a flashy user interface over a linux operating system.  To avoid any legal issues always make sure you own the license to use the operating systems you put on this drive and that operating system should only be on that single stick.

How to Handle Email
Email is best handled if you leave it on the web somewhere.  gMail, hotmail, or best of all you have a domain with your on email and a web based interface. Calendars(gmail) and tasklists, can usually be tied into a portable application, but there again, it is best to have them hosted somewhere.  Remember the Milk (task Scheduling)

Give Me Some Apps
As a web designer/developer I like to use software that is robust The software has active communities so each program can only become bigger and better.  Smashing has a great article that covers most of the FREE software out there. Smashing Magazine – “40+ Desert Island Web Development Tools” Here are some additional programs I highly recommend.  Aptana – Is a web development environment built on top of Eclipse. You can download Aptana as a stand alone install or as an extension if you already have Eclipse.  There are many plugins that you can use and I would highly recommend jQuery builder as one of those.
Navicat – This is an excellent program for working with your MySQL databases.  It’s a little spendy but worth it.  Think of it like MS SQL Administrator for the mySQL user and yes it has visual query building.