How about growing something on it? You could make or buy a trellis (or several) and grow clematis or roses on it. If you're in a zone with cold winters, you can choose something evergreen like ivy (this doesn't even need a trellis). I can't really tell from your description how much sun this wall would get, but you'd have to choose your plants carefully depending on the light.

http://img4-3.sunset.timeinc.net/i/how-to-books/00/wall-panels--l.jpg?400:400

How to make a cheap, functional trellis:

http://www.diynetwork.com/how-to/how-to-make-a-cucumber-trellis/index.html

Since the garage is right at the property line, perhaps your neighbor wouldn't mind if you DID paint the portion facing into your yard. Asking is the only way to find out.

HTH, Rosie

You might post an explanatory picture to see if it spurs other ideas.