Developers realised this and got to work. Projects and websites sprung up in a flurry. Popular and widely used open-source software were targeted, trimmed and re-designed to run smoothly from a removable drive. Websites like PortableApps.com and UsbApps.

com now offer portable versions of all the popular free software like Firefox, OpenOffice.org. You can now imitate your desktop environment with all your favourite software customised with all your preferred settings from your USB flashdrive.

Here in this article we take you through some of the most popular portable applications for your flashdrive. Almost all of them are available online.

Portable Firefox is a fast, easy to use, full-fledged web browser. It has all the great features of regular Firefox including popup-blocking, tabbed-browsing, integrated search, improved privacy features, automatic updating and more. Plus, it leaves no personal information behind on the machine you run it on, so you can take your favourite browser along with all your bookmarks and extensions with you wherever you go. If you spend a lot of time on computers that you don not own and long for the comfort of your Firefox that you have at home, get yourself a copy of Portable Firefox 1.5.

If you are looking for anonymous browsing, TorPark will give you an encrypted and anonymous IP browsing experience straight from your USB flashdrive. The browser is a combination of Tor (The Onion Router) and Mozilla's browser technologies. It sounds like a good idea when you are browsing on someone else's computer. It is available for download at torpark.nfshost.com

Portable OpenOffice.org is compatible (and, arguably, comparable) with Microsoft Office suite but without the price tag, lets you view and edit office documents on a computer with a USB port without installing anything on the hard drive. Mighty handy in situations where you don not have admin access or time to install the full version of the software. A 144MB version of free the office suite is now available for running from your USB flashdrive.

Portable Thunderbird is a safe and fast email client that is easy to use. It has all the great features of the regular Thunderbird including quick message search, customisable views, support for IMAP/POP, RSS and more.

Portable Sunbird is a standalone organiser and task management application built on the same technology as the Firefox. It is easy to use and keeps your calendar and tasks up-to-date.

Portable NVU is an easy to use web editor similar to the Microsoft Frontpage or Dreamweaver. Some of its features include a FTP site manager, tabbed interface, CSS editing, standard-compliant markup, fully customisable interface, a built-in spellchecker and more.

Portable Gaim is an instant messaging client that works with AOL Instant Messenger, ICQ, MSN Messenger, Yahoo and more. You can log on to multiple services with the same program, no need to open multiple instant messengers. All your IM settings stays the same.

Portable AbiWord is a free word processing program similar to Microsoft Word. It has the ability to read and write a number of document types. It includes grammar and spelling checkers as well as an array of other handy features.

PStart is a simple tray tool designed to run all these portable applications from the flashdrives or removable disks. The start menu provided is great for anyone who has a lot of portable apps on their portable drive. PStart is available at pegtop.net

None of these applications leave any information or files behind on the machine you run it on. For a more comprehensive list, head over to Wikipedia's list of portable applications at en.wikipedia.org/wiki/List_of_portable_applications

When you are away from your home or office, these programs might prove to be a real lifesaver. These programs do not just run from the flashdrives you can install them on any media that can be written on to, such as USB harddrives or shared network drives. People are even installing them on iPods and MP3 players, which can easily be configured to serve as external PC disc drives as well as music players.

Obviously the portable apps are getting popular for the convenience they offer. You can now use the same programs on every computer. And not only your data, You get to keep your settings, your bookmarks, your address book, all correspondence and files on your flashdrive or even on your MP3 player. Work at home, work at the office, work at some relative's, any place there is a computer you are able to function the way you like it.

But there are some issues: flashdrives are only detected automatically by Windows XP, 2000 and ME. Earlier Windows versions require you to install a driver for the drive, meaning you have to carry a CD containing the driver when you are on the road. Which partially takes out the edge of portable apps.

A secondary issue: Older systems may have USB 1.0 hardware, which has much slower transfer rates than the current USB 2.0. USB 1.0 is painfully slow when it comes to loading software; although they work pretty well once it starts running. With USB 2.0 you would have no problems. You can upgrade to USB 2.0 by inserting a PCI card with more ports.

Nevertheless, portable applications are getting kudos from backpackers and travellers, students and soldiers in Iraq and Afghanistan. For a lot of people portable functionality is more important than nitpicky obsession with features of many mostly Microsoft programs.

One last note here: scan your pen drive for viruses periodically. In the old days, viruses spread through disks, not through the Internet. The same potential threat is there today when you move programs and files from computer to computer.