Take Your Favorite Software Everywhere You Go with PortableApps!

Now you can take most of your favorite Free Open Source Software in your USB Flash Drive. Project called PortableApps makes it easier for you. It provides pre-compiled binaries for Windows and nice Program Launcher with autorun and other configuration files. So all you have to do is install the PortableApps on your Flash Drive.
PortableApps currently have portable versions popular applications like Mozilla Firefox, OpenOffice, VLC Player, 7-Zip etc. (Full list of portable applications available at PortableApps) which can be installed separately according to your likings.
They also provide PortableApps Suite which has collection of some popular software and cool PortableApps.com launcher/menu which is shown on the image. That launcher will skip the task bar and only show its icon on the notification area.
PortableApps Suit comes with 3 editions:

• Standard Edition: ClamWin Portable (antivirus), Firefox Portable (web browser), Gaim Portable (instant messaging), OpenOffice.org Portable (office suite), Sudoku Portable (puzzle game), Sunbird Portable (calendar/task manager) and Thunderbird Portable (email client) and runs comfortably from a 512MB drive. Size: 89.5MB (download), ~260MB (installed)

• Lite Edition: Uses AbiWord Portable (word processor) instead of OpenOffice.org Portable and runs comfortably from a 256MB drive. Size: 30.4MB (download), ~105MB (installed)

• Base Edition: If you'd like to pick and choose exactly which apps to include, you can try Portable Apps Suite (Base Edition). This is a stripped down package with just the PortableApps Menu, PortableApps Backup utility and custom folders, icons and autorun. It's less than 1MB installed, so it's a great option for smaller drives. Size: 0.7MB (download), 1MB (installed)

I like the Base Edition because I don't want all the applications in the Lite or Standard edition.
You can install portable applications by clicking on the Options menu and selecting Install New Application.
Then you have to select the downloaded portable application and you are just one click away from installing it. ;-)
To make full use of the PortableApps menu/launcher keep your files on Documents directory and Music Files, Images and Videos on Music, Pictures and Video directories respectively within the Document directory in the Flash Drive.
BTW At the moment my Flash Drive has Firefox, 7-Zip, VLCPlayer and ClamWin with Base Edition and all it takes is 43.2MB :-)