iTerm as VisoriTerm2 is a replacement for the built-in Mac terminal app. It provides many terminal features you may be used to from other systems (ahem, Linux), as well as some unique features and tools.
When it comes to OS X integration, iTerm2 has some amazing capabilities. You can even configure it to emulate Visor. Here I explain how to configure iTerm2 to slide down from the top of the screen like a Quake-style Visor. You can get an idea of what this looks like from the image on the left (click on it for a full-sized version). The borderless terminal window slides down from the top when focused, and then slides back up when not used. Never again will you need to hunt through your open windows looking for the terminal.
By mapping the visor to a hotkey, it becomes easy to quickly access a shell wherever you are without even taking your hands off the keyboard. And then, just as easily, the terminal can be dismissed. This article explains how to set up a visor-like terminal and then map a hotkey.
You can set up iTerm2 to do this in only three steps.