I used Illustrator to convert a client's CAD files to shaded and color rendered objects of a bus shelter and bench. For a city proposal they had to look like they are made of steel and painted green.
These were extremely complex files since CAD created only a single line for the objects on the left. To make them into complete shapes that could be filled with colors and gradients, many paths had to be duplicated and joined.
AutoCAD generated an incredible number of layers in Illustrator, so the Layers palette was the key to organizing all these numerous elements. The nice thing is that all the elements came across perfectly from the CAD file with the scale and dimensions intact. Illustrator made it easy to create more realistic representations of these objects.
The wife of the owner of a new company liked a pin she had of a gecko on a branch.
I traced around the gecko on the photo of her brooch using the pen tool to create the logo, then scatter brush elements for the little bumps on the skin.
A DVD package mock-up (if my cats starred in their own feline feature film) done with the 3D Extrude effect in Illustrator and the artwork mapped onto the object's surfaces.
T-shirt and badge designs created for a clothing company.