Windows: Quick Menu is a free tool that enables you to launch programs with a tap of the middle button of the mouse.
The application is portable, so no installation is required - simply unzip the download and run the file inside. It creates a folder called "shortcuts", where you can place your applications and subfolders you want quick access to. Restart the program, then press Ctrl and the middle mouse button to quickly pull up the launch menu and click the program you want to launch. (Not all mice have a middle button; some let you click the scroll wheel or click both buttons at once for the same effect.)
Quick Menu only does one thing, but it does it well and it's a free download.