Few days ago I’ve got the quickest way to run console commands in Gnome. There are three utilities known providing pop-up console: YaKuake, Tilda and Yeahconsole. All of them are included into Ubuntu apt repository and can be installed by corresponding commands:
sudo aptitude install yakuake
sudo aptitude install tilda
sudo aptitude install yeahconsole
At the next screenshot you can see all three utilities run at my laptop. Of course I don’t them all at once but prefer Tilda as the most comfortable for me. YaKuake is designed for KDE and uses konsole to emulate terminal. Tilda and YaKuake have GUI configuration tool when Yeahconsole is configured by editing configuration file /usr/X11/Xresourses.