I work hard to keep my garage organized, and at least maintain the ability to put two cars into my two car garage, even if we normally only park one in there. I have 7 arcade cabinets around the edge, and lots of shelves. The secrets for me are:
1. Carefully mapping out my space using Google Sketchup. This allows me to play with the arcade cabinets, cars, shelves, etc...in a virtual space that's accurate to the inch.
2. Hyloft Ceiling Mounted Storage shelves from Home Depot. I have 8 of these sets of shelves that hang from the ceiling. It creates a ton of storage out of otherwise wasted space. This allowed me to move many things I'd have stored on the shelves around the edge of the garage.
3. All games on Waxman 2" Rubber Locking Swivel Casters from Lowes. This makes moving games on the cement garage extremely easy. Very nice for moving things out of the way temporarily, and rearranging when necessary.
Garage arcades are must for some of us.