I believe this will end up being a multi-stage process though it was not originally intended to be so - having said that, here's the first part:
We have four bedrooms in our house - the master bedroom, my daughter Grace's room, a guest room and since we moved in, I've used the fourth bedroom as my office. It is adjacent to our bonus room which is the source of a lot of noise and interruption of work...and gaming. After reminding my wife we would no longer have a guest room when our second baby arrives (the baby gets the guest room as her bedroom) it was fairly easy to convince her I needed to remodel a part of our third garage stall into an office for me. Daddy gets a cave.
So, I set forth on a quest of my own making. Many times I visited the sages Home Depot and Lowes and eventually framed a wall in our third garage stall, insulated it, blew insulation into the existing walls, added two outlets (yes, I even had a permit

), sheetrocked it and painted it a dark green. At 11:45 last night I moved the last of my stuff to my new office, complete with air conditioner, small fridge, a bunch of cabinet and shelf space and a whoooole lot of peace and quiet in which to work and game. I've left one wall essentially bare in anticipation of painting an 8' x 4'6" rectangle for use with a projector.

It was a massive project to tackle alone but as I'm sitting here now...I'm very glad I jumped in. Now if you'll excuse me, I need to go stock my fridge.
PS: I'll add some pics in the next couple days or so once I get all the stuff put away.
PPS: It's a ways from being all done but at least all the junk has been squirreled away.
As you enter the office:
Turning towards your left:
And turning again to the left, facing the door:
The huge open space above my monitors (best seen in the first picture) is going to have a screen either painted on or attached to the wall which will be the viewing surface for a DLP projector to be placed on top of the silver wire shelving seen in the last shot.

I have a bunch of ideas I'd like to do to dress it up a bit but I didn't want to spend a pile of cash on this project - at least not all at once.