Likewise, the portable edition of OpenOffice behaves strangely if you don't have the PA suite folder installed on the root folder of a drive. When I tried running it from my desktop, it crashed, but after moving it to a thumb drive it worked perfectly. Also, because the PA suite is self-contained and doesn't install anything on your PC, things like document-type associations (for instance, for OpenOffice documents) won't be created. Finally, if you use the PA suite launcher on Windows 2000, there is (as of this writing) a bug that causes the launcher to crash -- there is a patch for it.
The PortableApps suite isn't the only prepackaged collection of portable programs out there. Consider the far less ambitious but still impressive Floppy Office, which packs a nifty array of tiny little productivity tools into a mere 1.5MB archive.
If you're not interested in a suite, there are a lot of apps out there that offer portable versions. For example, there's a nice version of the Opera browser , which some prefer to Firefox. And if OpenOffice is not to your taste, you could swap it for a portable version of the Scribus word processor and page-designer application.
If you're still not satisfied, Listible.com has a whole subcategory devoted to portable productivity applications.
Finally, I should make mention of Nirsoft, maker of a whole collection of incredibly useful and free utilities, all of which require no installation and will run from thumb drive or CD alike. They're perfect if you want to assemble a Swiss-army-knife USB collection of utilities; the program ProduKey alone, which recovers product keys for Windows, Office, and a number of Microsoft server applications, is a must-have.
Run A Standalone OS
It's not only possible to run standalone applications from a USB drive -- it's also possible to boot and run a whole standalone operating system from one, too.