For anyone else who is interested, I created a slightly modified version of Todo 3.0 which can run off of a flash drive or similar device. Rather than requiring an install, it simply stores the Todo list in an xml file in the same directory as the .exe file.
Please note that you need to fully close Todo 3.0 before pulling your flash drive out. That means you have to do File->Exit at the main window (or right click on the system tray icon, and selecte “Exit”). If you don’t do this, it won’t save any changes you have made to your Todo list.
You can download Todo 3.0 Mobile Beta here.