Synapse is a semantic launcher written in Vala that allows the user to easily launch applications as well as search for documents through searching Zeitgeist..
The launcher built into the KDE Plasma desktop. While its basic function is to launch programs from a sort of mini-command-line, its functionality can be extended by "runner...
Plank is the default dock in elementary OS as well as a the underlying tech behind the Docky dock. Plank is a bare bones dock for those looking for something simple to launch app...
DockbarX is a stand alone dock that groups and launches applications.
GNOME Do is an app launcher that also allows searching online and offline.
Launchy is a cross platform app launcher that also launches documents, folders and web browser bookmarks.
Cairo-Dock is a Mac like dock for easily launching applications that is themeable and has a built in stand alone DE session.
Avant Window Navigator
Avant Window Navigator is a Mac like dock that launches applications.