A good place to start is http://www.designsbymark.com
Other than that, I browse around Club Si's photochopper forum and pick up ideas and hints.
Here's another I did:
<img src="http://63.102.174.92/yellowGK.jpg" border=0>
<img src="http://www.hyundaiperformance.com/upload/4doorGLSig.gif" border=0>