Krunner's abilities can be extended with a slew of plug-ins.
When you press Alt + PF2 in Gnome you get the 'Run Application' dialog. The Run Application is smarter than the Windows run command, but is nowhere close to Krunner's abilities. When you type the program name for application in, you have to start with the exact name. For example: you can't type terminal, you have to type gnome-terminal.
The best alternative is to use a utility called Gnome-Do. Install Gnome-Do via the package manager.
You can bring up Gnome-Do by pressing the Super Key and Space bar together. Then you just start typing part of the name of your application and Gnome-Do will find it for you. Press enter and Gnome-Do will run the application. Press the down arrow and Gnome-Do will bring up additional options.
Gnome-Do can also be extended with additional abilities with the use of plug-ins.
Between Krunner and Gnome-Do who needs menus anymore ?
