I've seen a variety of different types: traditional (single-sided) cards, dual-sided cards, high gloss and semi-gloss cards, and even some with holograms on them for those willing to spend a lot. A few times I've run into people giving out mini CDs (the 125mb and 250mb CDs) along with their business cards for technical industries. What kind of cards do you have? Do you feel that your design is best for what you do? And would you change it from what you have now if you felt it would make a better impression and impact upon your clients and your business?