Don’t want to wait for you terminal application to load, and don’t want to have to switch between it and your other windows?
Tilda is a terminal similar to those found in first person shooter games such as Quake. Tilda runs constantly in the background until it is triggered to appear by a shortcut key.
Tilda can be installed from the tilda package in the Ubuntu repositories.
Launch Tilda from the Accessories menu. A terminal will appear the the upper-left of the screen. The default key to toggle Tilda is F1. Close Tilda completely by typing exit in the terminal.
Tilda supports tabs. Open a tab by right mouse clicking and selecting New Tab. Close a tab by typing exit or by selecting Close Tab in the context menu.
Right mouse click and select Preferences to configure Tilda. The first thing you will probably want to change is the width and height of Tilda in the Appearance tab. Scrolling can be done with the mouse wheel or by enabling the scrollbar in the Scrolling tab.
Here’s my own customized Tilda terminal:
[update] Also check out the similar application, Guake.