Keypirinha - A lightning fast and flexible keystroke launcher for Windows. No installation required (portable).
Flashlight - Control your Mac with a keystroke.
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.
Tiny Flashlight + LED - Tiny Flashlight + LED is free to use application that can be used anywhere else, having nicely built-in functionality.
Listary - Listary is a revolutionary search utility for Windows
Simple Flashlight - A clean flashlight with an extra bright display and customizable stroboscope.