I have small areas of 3D, but there are some people out there doing truly amazing things. There are plenty of examples of them in the Springfield Showcase section, and some even have instructions. Way too many to list, but use the search option and you should get heaps of ideas.
These are a starting point:
http://forum.ea.com/eaforum/posts/list/9832861.page
http://forum.ea.com/eaforum/posts/list/9815015.page