GNOME Do


GNOME Do is a free and open-source application launcher for Linux originally created by David Siegel, and currently maintained by Alex Launi. Like other application launchers, it allows searching for applications and files, but it also allows specifying actions to perform on search results. GNOME Do allows for quick finding of miscellaneous artifacts of GNOME environment and execute the basic actions on them.
While it is designed primarily for the GNOME desktop, it works in other desktop environments, such as KDE.
GNOME Do was inspired by Quicksilver for Mac OS X, and GNOME Launch Box.

Docky

Docky is a theme for GNOME Do that behaves much like the Mac OS X dock. Unlike GNOME Do's traditional interface, Docky can be set to one of three modes for hiding:
Standard Do functionality is still present within Docky, and the Do hot-key will still produce the expected behavior.
Docky 2 is a separate application from GNOME Do. Integration with GNOME Do is planned for Docky 2.