Veronica Hebard uses a simple card, but I like how interesting it is. I think if I were to make a card I'd want something simple and engaging like this, with only who I am and a way to contact me/see my work.
Kate Slater made some promotional booklets to mail off and show off her work...I really like that idea. It's small, portable, can be revisited and displays a lot. Maybe a promotional tiny sequential booklet for myself?