There are programs that require no more than to be unzipped, can be used on multiple computers, don't write to the registry, and fit neatly on your flash drive. These are called portable programs and there are hundreds out there. I'm going to give you the ten you won't be able to live without.
OpenOffice.org is one of the most well-known competitors to the Microsoft Office suite. OpenOffice comes with a word processor, spreadsheet program, database program, and even a math and a drawing program, all at a great price: free! The program even reads Microsoft Word documents, including that pesky .docx format, and the setup is similar to Microsoft Office, meaning an easier transition to OpenOffice. In fact, OpenOffice was one of the first portable applications I ever used.
Firefox Portable 3.0.14
Firefox is another alternative to a widely-used Microsoft product: Internet Explorer. Firefox is a free, open-source web browser made by Mozilla, the same people that brought you the Thunderbird mail client. What makes Firefox such a great tool isn't the fact that it does everything Internet Explorer does but the thousands of extensions that do everything from downloading torrent files to finding good SEO keywords. Just like OpenOffice, Firefox Portable does everything fully-installed Firefox does except it can be taken with you on your jump drive. Neat, huh?
If you find yourself downloading suspicious files, the last thing you want is to infect your jump drive that you use on multiple computers which might not belong to you. Enter ClamWin Portable. ClamWin is pretty good antivirus software, and the portable version is no different. ClamWin is a very powerful antivirus engine with high detection rates and regular definition updates. Unfortunately, it lacks an on-access virus scanner, meaning all files will have to be scanned manually, and automatic updates and scheduled scans are not available in the portable version.
Windows XP does not have native support for burning DVD. Vista does, but since a lot of people don't like Vista, you may be stuck on a Windows XP computer needing to burn a DVD with no way to burn one...but not anymore! Infrarecorder Portable burns both CDs and DVDs. It can burn data disks, video disks, audio disks, disk images, and even bootable cds. The full version comes with an audio CD ripper, but due to copyright infringement issues, must be downloaded from the site.
The .rar format is one of the most popular compression formats available, and I, for one, can't live without WinRAR, which became a problem when I needed to unzip .rar files on other computers. Luckily, I came across WinRAR Unplugged, the portable version of WinRAR which supports not only .rar but .7z, .zip, .gz, and more! It supports password-protected files and broken up archives (files with that pesky .001, .002, etc. extension). WinRAR Unplugged is not free, but there is a trial version available.
Free Download Manager
Free Download Manager is just that: a free download manager. It splits files up into parts and downloads those simultaneously to increase downloading speeds. It supports torrent downloading and flash video downloading if you like to download YouTube videos. It has a spider that will allow you to download whole webpages or pieces of a webpage (why anyone would want to do this is beyond me, but if you want to, you can). It has a scheduler and a tool that allows you to download only the files you need from a zip file. It can download from several mirrors at the same time and if you're worried about viruses, you can read what other people say about the file right from the download manager window. For the techies who care, the program is now under the GNU Public License, meaning that you can download the source code if you feel like adding anything else. To get the portable version, you must first install the fuill version, then go to file>create portable version to make it portable. Once created, however, it can be uninstalled.
GIMP stands for GNU Image Manipulation Program. In other words, it's a free and portable version of Photoshop. GIMP has many of the features of Photoshop but if you're too used to Photoshop, it'll take some time to get used to this program. GIMP does painting, image manipulation, animation, layers, batch processing, and a lot more. GIMP was written under Uni, but is compatible with Windows.
PortableApps App Compactor
By now, you have a lot of apps taking up a lot of disk space. Even if you have 16 gb of space on your jump drive, it wouldn't hurt to have a little more. That is where the app compactor comes in. PortableApps App Compactor compacts your apps without affecting functionality. It uses 7-zip compression and claims to shrink files to only 50% or less of their original file size.
While some coders rely on WYSIWYG (what you see is what you get) programs, others enjoy the control you can get with hand-coding. However, even the most adamant hand-coder would appreciate a little help and that's when Notepad++ comes in. Notepad++ is like an upgraded version of Notepad optimized for coders. It features syntax highlighting and folding for many different program languages including C, C++, HTML, ASP, Java, Pascal, CSS, and many more, including user-defined syntax highlighting. Notepad++ has full drag n' drop support, meaning you can drag code straight into the program, and a nice zoom feature. Notepad++ supports many languages and as a portable program, you can take it with you, so it's perfect for the coder on the go!
Skype is a program that needs no introduction. It's used by many people, including college students and people who like to keep in touch over long distances. With Skype Portable, you can call other people who also have Skype for free and you can call everyone else for either a low monthly plan or on a pay-as-you-go rate. When you're offline, you can have calls forwarded to your phone. Skype is perfect for those who have friends or do business overseas.