I use the program Visor to give me access to a terminal from any program.  I press 'Control' twice and it slides down from the top.  It is about as fast quicksilver to run a command from any window.

Here is the main site:
http://visor.binaryage.com/

Here are some instructions for improving it:
http://tech.xster.net/tips/the-perfect-visor-reborn/

However, I personally do not like making it an LSUIElement because long story short I can't figure out how to change the transparency with a keyboard shortcut.  Instead, I use DragThing and exclude Visor from the dock and application switcher.

I can't recommend this program enough.  I can't live without it since I use the terminal constantly and this gives me the ability to use bash aliases and scripts as fast as I can access a quicksilver catalog item.

Also, DragThing.  Stupid name, but it replaces your boring normal dock with as many themed and tabbed docks as you have crap to shove on them.  It is also a more versatile and better application switcher than either Witch or LiteSwitchX.  

Brandon