Keeping multiple terminal windows in focus

Try Terminator. It allows you to split the terminal window (You can also have tabs and separate windows).

You can install terminator from your current terminal with this command:

sudo apt-get install terminator

Or you can search 'terminator' in Ubuntu Software Centre (or Synaptic).

Both screen and byobu (which is just screen with some neat extras) allow you to use multiple windows within one session. For me they're must-have applications when I'm connecting via SSH.

See https://help.ubuntu.com/community/Screen for more information on how to use screen.

Yakuake is like Guake + Terminator: you get multiple tabs and split screen terminals, all in a quake drop-down. But it's a KDE application so if you're using Gnome, I would say Guake.