DockbarX - DockbarX is a standalone dock that groups and launches applications.
Slingscold - Slingscold is a lightweight application launcher similar to Launchpad in Mac OS X.
Gnome-Pie - Gnome-Pie is a circular application launcher for Linux.
Listary - Listary is a revolutionary search utility for Windows
Synapse - Synapse is a semantic launcher written in Vala that you can use to start applications as well as find and access relevant documents and files by making use of the Zeitgeist engine.
Scherlokk - Mac OS X application. Simple and user friendly, Scherlokk will find your media and missed files - quickly.