Windows only: If you're looking for a portable application menu and launcher, Appetizer is a free, polished, and highly customisable open source candidate.
Appetizer can be installed or run as a portable application. On first run, Appetizer offers to import shortcuts from your quick launch menu and start menu. If you use the default PortableApps format for file storage on your USB drive, Appetizer will import your portable applications and media.
That's nothing particularly new, but Appetizer is skin-able and has support for plug-ins. The launcher can be resized, too, from the format you see in the screenshot here, to run instead along the top of the screen, or on the side of it like a more traditional dock. You can assign a hotkey to launch Appetizer, and create special keyboard shortcuts within Appetizer for system functions like opening the Control Panel and Recycling Bin. If you're interested in using an application launcher but aren't sold on Appetizer, make sure to check out the Hive Five: Best Application Launchers. Appetizer is open source, Windows only.