I originally posted this in 2008, while running a crappy dell machine, and therefore I was using all sorts of portable apps. However I still believe it useful to a lot of people, so, here you go!
Easily the most powerful open source browser is also availible in portable form. You can even save your bookmarks, addons, and history right to the usb.
2. NVU Portable
Easy Html coding on the road with NVU. Whenever I need to code something in HTML really quickly. Download
3. GIMP Portable
Open Source Photoshop-like program. Portable edition helps so you don’t have to install all the stuff on your computer
My FTP client of choice. Runs fast and allows you to upload on the fly.
Great program for watching a lot of Video and Audio formats.
6. Open Office
Similar to Microsoft Word, this document editor has much functionality
Unzips many file formats, such as RAR and ZIP
8. Foxit Reader
Instead of using Adobe’s slow and junky PDF reader, use this free one thats fast.
9. Miranda IM
Instant Messaging Program that works with AIM, Jabber, ICQ, IRC, MSN, Yahoo, Gadu-Gadu and more.
10. Double Killer
A simple program that scans your hard drive for duplicates.