Keypirinha - A lightning fast and flexible keystroke launcher for Windows. No installation required (portable).

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.

dmenu - dmenu is a dynamic menu for X, originally designed for dwm.

DockbarX - DockbarX is a standalone dock that groups and launches applications.

j4-dmenu-desktop - A replacement for i3-dmenu-desktop Its purpose is to find .desktop files and offer you a menu to start an application using dmenu.