This only really works if you have a garage, so that rules most of us out in London, but for those lucky enough to have somewhere to keep their cardboard boxes full of stuff that should have been thrown away years ago car, how about transforming the door?
Style-Your-Garage sells rather wonderful pictures of what you might like to have in your garage. They are very convincing, and according to the website, very easy to use. We suspect sticky-back-plastic is involved somewhere. I'd like the elephant, but I suspect MAD would want the picture of the Harley. Or the boat.
The website has many, many pictures and there's world wide shipping. There's even a handy little gadget for you to see what your garage (or something similar) would look like with your chosen design. I don't know why I think of garages as middleagedad territory, but I do. Even if you don't buy this for him for Valentine's day, he might like to look at the website and dream.