I have none, and not really considering getting one.
I'm not totally opposed to it, but it would have to conform to a huge set of standards, such as:
- no cliché themes. I tire of seeing tribal/dragons/tiger/memorials/portraits/koifish/fairies/etc all the time. Besides, i have no idea what i'll like in 5 years, let alone the rest of my life.
- view-ability. Some might look good up close, but look like indistinct blobs of color at a distance, so it would have to be fairly large, but still not look sloppy in close detail. Plus, there's the matter of color decay over time, so it would have to be with only black or with very saturated color, which are harder to pull off aesthetically.
- organic. The body is a very irregular canvas, and i never understood why most tattoos work against our shape (placing at the most regular surfaces, based solely on size and availability, etc) instead of working with them. A design specifically tailored to conform to our shapes sounds much more interesting.
So, if i eventually did something, it would have to be a one-shot design for large portions of my body, with large details, and perhaps small details up-close that don't mess up the larger picture, well outlined, and with strong and few colors (probably just black). Tricky, right? Perhaps something like the Guild Wars ritualists [http://eu.guildwars.com/gallery/view-wallpaper/139/]...