If you're a PHP developer, you can use EasyPHP to set up a WAMP (Windows, Apache, MySQL and PHP) server on a thumb drive. It also includes de-bugging and development tools like PhpMyAdmin and Xdebug. Operating System: Windows.
Another option for creating a portable WAMP stack, Z-WAMP aims to be lightweight and easy to install. Additional applications included in the package include Adminer, MongoDB Admin, MemCached, SQLite, eAccelerator, and Alternative PHP Cache (APC). Operating System: Windows.
Bring your virtual sticky notes with you with PNotes. This app requires no installation and includes features like spoken notes, scheduling, password protection and encryption. Operating System: Windows.
Just 609 KB, this portable time tracking app offers an intuitive interface and plenty of reporting features. It's Java-based, so it will work on just about any system. Operating System: OS Independent.
To Do List
45) Task Coach
This portable scheduling tool gives you the ability to break large tasks into smaller sub-tasks and mark them off when completed. It's also compatible with Outlook and Thunderbirdallowing you to drag and drop tasks from one app to the other. Operating System: Windows, Linux, OS X.
46) BleachBit Portable
Take this app with you to protect your privacy when using someone else's PC. It cleans up your cache, temporary files, cookies and Internet history, and it includes a shredder to eliminate all traces of erased files. Operating System: Windows.
47) Portable Keyboard Layout
If you learned a different keyboard layout or want to try an alternative to the QWERTY keyboard to prevent carpal tunnel and repetitive motion injury, this app is for you. Just plug it into your system and it will transform your keyboard into the one you've set up on your thumb drive. Operating System: Windows.
48) Folder Menu
This handy tool makes it easier to jump to your favorite files and folders. It works with Windows Explorer, open/save dialog boxes, or the command prompt. Operating System: Windows.
Appetizer is a dock-style application launcher for Windows (2000, XP or Vista). It supports the PortableApps.com file format, so it will automatically detect any other portable apps you have on your thumb drive and include them on the dock. Operating System: Windows.
50) BackTrack Linux
The "most widely adopted penetration testing framework in existence," BackTrack includes a complete Linux distribution with an up-to-date set of tools for penetration testing. Easy instructions for downloading it to a USB drive are included on the site. Operating System: Linux.