There is actually heaps of these around the world.
http://www.vendian.org/mncharity/dir3/solarsystem/
This link takes you to the list of a lot and a link too.
I just started building a model Solar System for my sons' room. We are going to paint a big sun one upper corner and spread the planets across his room. I am currently trying to make my foam balls as smooth as possible as any little blim blam will show up badly in this scale.
Has anyone else had a go at making one?
Cheers for now
Andrew