Lean to's, blisters on the outside of the garage, a separate shed- all of this has been done. It's just a closet essentially. Ventilation can be done with an attic fan or just good venting from the bottom and out the top with soffits.
Things to consider-
Power. How are you going to get the power to there? Buried? Overhead? Through the wall?
Air supply back to the garage. Again, buried, overhead or through the wall? Plan on having moisture traps at both the compressor side and at the point it enters the garage since you might have to go up or down in the pipe runs.
How will you service the compressor? Make sure it can fit through that door way- don't build it with the compressor in place in case you have to remove it some day. A removable side panel may be worth the effort there, plus a normal door. Or just a bigger door way which is the easiest of all.
As for pictures, I haven't seen many, but they are available if you use the search option. Look for keywords of 'air compressor' and 'shed' or 'enclosure'. You'll find a few threads on it.