GNOME Do is fantastic. I’ve got it mapped to the same keys Quicksilver used and it’s just great.
To set the hotkey that brings up the window you can type in, right-click the purple icon in your status bar and click ‘Preferences’. A window will pop up- click the middle tab ‘Keyboard’. There you can type the keys you want to use to activate GNOME Do in the ‘Summon’ field.Install via Software Center: GNOME Do
How Good is the Linux App?
App name should be marketable
Has a nice app icon
Uses Tango icon guidelines
Slick UI that's fun to use
Killer feature people talk about
Top-level domain name
Site has FAQs for users
Site has a User forum
Site has a way to contact the developers
Packages for Ubuntu, Fedora, and openSUSE