Terminator is a terminal emulator which supports multiple terminals in one window that you can arrange in whatever way you want. Besides the grid, Terminator also supports tabs and comes with many useful features.
Terminator 0.94 which was released today got a really new cool plugin called "watch terminals for activity" which displays a notification bubble (in Ubuntu it uses NotifyOSD) when there is activity in a certain terminal you want to watch. This has many different uses like getting notified when a download (using wget or whatever) completes and so on.
Terminator 0.94 also comes with a screenshots plugin - which can take screenshots of individual terminals, as well as many bug fixes.
Terminator 0.94 is not yet available in its PPA, but you can install it via the WebUpd8 PPA (which is not almost stable - there are only stable packages except gThumb - we package development releases because of the many new features compared to the stable version). So to install Terminator 0.94 in Ubuntu Karmic, Lucid or Maverick, simply paste the following commands in a terminal:
sudo add-apt-repository ppa:nilarimogard/webupd8 && sudo apt-get update sudo apt-get install terminator