There are plenty of different terminal programs out there for all different desktops. Yakuake is one such KDE-based terminal emulator with a difference.
It basically gives you a Quake-style drop-down terminal at the top of the screen, which you can access with a single keystroke. Installing Yakuake is extremely simple, especially if the application is your repositories. In the case of my Kubuntu system, a simple:
$ sudo apt-get install yakuake
was sufficient to get up and running. If not, you can download the sources or a static .deb from the Downloads page.
Once you're installed, start the application by pressing Alt-F2 and entering yakuake. You'll get a quick notification that it's up and running.
By default, the key you need to press is F12. The terminal area slides down from the top of the screen and then you can use it like any other terminal. Pressing F12 again will hide it - it's a toggle key.
The benefit of this system is you can start off a task in your Yakuake terminal and hide it. The task will stay running and you can check its status again with another keypress.
Yakuake also features multiple tab support; clicking the small plus button at the bottom and on the left allows you to open multiple tabs and therefore run multiple terminal sessions.
A drop-down terminal can prove useful for anyone (like me) who always wants a command line interface at their fingertips and really can't be beaten for speedy access. Yakuake is of course, designed for KDE and you can find out more on the official website.
Screenshot taken from the Yakuake screenshots page.
UPDATE: links updated to new website and capitalisation of Yakuake corrected.