There are a few ways to create custom keyboard shortcuts in Ubuntu Gutsy 7.10 but I found the following way the easiest. This guide will explain how to make gnome-do, a launchy and Microsoft/Vista/Instant Search type tool, a keyboard shortcut at Alt+Space.
Install Advanced Desktop Effects Settings (ccsm) in Add/Remove…(Applications -> Add/Remove…). Restart.
Run Settings Manager (System -> Preferences -> Advanced Desktop Effects Settings). Click on General Options (General -> General Options). Click the Commands tab. Type your command. For example type gnome-do at Run Command Line 0.
Click Actions tab. Expand Commands. Under key, t your command line number, click disabled and press your shortcut. For example press Alt and space to make a shortcut that runs on Alt+space.