Want to take you application with you on a usb? Want to have you apps made portable so you dont need to install them? then try http://www.eure.ca/ it lets you create you own portable apps so you can have AV or email on your pen drive
The following site is a great source for portable apps. There is just about everything you might need such as FireFox, Thunderbird, Open Office, Gimp, VLC, PuTTY and lots more. http://portableapps.com/suite For anyone who is familiar with TrueCrypt (http://www.truecrypt.org/), it is possible to install the portable apps suite into a TrueCrypt 'encrypted container', which not only protects the applications and any associated files you may have created with them, but which can be copied to whichever device you want to store and run the applications from (USB Stick, PC, laptop).