If you're like me, you use the terminal almost as often as you use GUI's, so a drop-down terminal is a godsend. KDE has Yakuake, which is great if you use KDE (and I did for a while). If you use Gnome, though, it would seem that you're out of luck. The two options available are Tilda and Guake. Tilda can be rather buggy, but is overall very similar to Yakuake in its configurability. The bugginess really...well, bugs me, though, so I took a look at Guake. Guake feels much more stable, but it doesn't have the "drop-down" animation that i've come to love. There is a workaround for this though.
1) Download the source from here
and do the usual song and dance to install from source
2) In CCSM, go to the "Open" tab under Animations.
3) Add a new entry to the listbox
4) Select Burn for the effect, and set the duration to around 750-850 ms.
5) In the "Options" field, type the following:
fire_life=0.1, fire_particles=100, fire_size=0.1, fire_slowdown=0.1, fire_direction=1
6) For "Window Match" put this:
7) Click close.
8) Double-click on the first entry in the listbox, and add the following to the end of the Window Match field:
and click close
9) Repeat the above steps for the "Close" tab
Now start up Guake and hit F12 to see the pretty new effect.
I apologize to any veteran users I may have offended by posting a how-to simply for adding eye candy. :P