The default application launcher that provides a click-through interface for finding and launching applications. Kickoff has a search facitility, allowing you to type the name of the application or its description to find it.
Lancelot is a powerful application launcher which also allows launch menus to be placed on the panel. Lancelot provides search facilities, so if you know the name of the application you don't need to find your way around the menu.
There is also KRunner, which replaces the "run command" dialog, blurs the lines between desktop search, application launcher and command executor and provides a quick way to run applications or open documents.
