I learnt a lot about this in the type module and what I need on my business cards is my logo, name, web address, contact information (usually tel & email).
Here are some I made in the type module...
I need to think about colour and it MUST work in black and white.
Think about the quality & processes used.
NEED TO USE IT:
print collateral (stationary, business cards, mail outs, invoices, etc)
online (websites and Creative CV's)
It needs to be simple, memorable, timeless, versatile and appropriate.