Keep a terminal application open all the time? A drop-down terminal such as Guake might suit you better. A drop-down, or Quake-style, terminal stays hidden until you call it up with a key combination.
Guake is easy to configure, supports tabs, and works fine with Compiz desktop effects turned on. I’ve also written before about a similar application, Tilda.
Guake is a fairly young project and is not available in the Ubuntu repositories yet. Download and install the latest Debian/Ubuntu package from their download page, or click here for the latest 0.3.0 release.
Once Guake is installed, launch it from Applications->Accessories->Guake Terminal. You’ll see a green icon in your notification area. Press F12 to toggle displaying and hiding the terminal.
By default, Guake uses a semi-transparent black background and displays on the top half of your screen. Open a new tab with the button on the right of the bottom toolbar or by pressing Shift-Ctrl-T. Switch between tabs with Ctrl-PageUp and Ctrl-PageDown or using the buttons.
Guake is very configurable. Open the preferences by right-clicking in the terminal or notification area icon and selecting Preferences. It’s simple to change the size, position and appearance of the terminal. Use the Keyboard Shortcuts tab to configure key bindings. You can even keep the Guake terminal open behind the preferences window and see your changes live.
To start Guake automatically when you log in to Ubuntu, open System->Preferences->Sessions. Click Add, and create a new item with the command field set to guake.