Business cards are your chance to make a first or last impression -- it's always good to have something that is slightly cumbersome and interesting.
Since you likely won't have minifig business cards like some LEGO employees, you should consider making your own out of LEGO bricks.
Evil Mad Scientist Laboratories has apparently put aside their nefarious world-dominating plans to post a tutorial on how to print water-slide decals onto LEGO business cards (via Make Magazine). The results look like a fun (if slightly costly) way to introduce yourself. Although depending on the style of pant you favor, you might be looking at carrying one card at a time.