I print my own business cards using Printmaster (other programs are available) and I customize one for each of my sites. I also have an "I have visited you" card I leave in caches I find.
Using Avery card stock they are adequate and I find them disappearing pretty fast from my sites.
For my caches I give the name, geo coordinates, date placed, My name, and the Geocaching web link. (yes, this does mean revisiting the cache, but you should anyhow.