Business cards need to show what your about and show your talent.
So what I did was show what my hobbies are and show my personality on the card by layout and colour.
This is what I produced:
5 pictures of my work past present, packed in a CD case with my business card inside which can store many business cards and on the of the case explains what sort of person I'm personalty and work wise.
This is the front part of the cd:

The open up poster inside:

CDs that tare of into business cards:

Back of Cd with bullet points about myself like CD tracks:

Design for my own letter head: