Now that bhante has answered, I'm going to go off topic a bit....
Just as a personal preference, I'm not a fan of the "dharma" tattoos that seem to be getting more popular with Buddhists my own age. I understand that there's no explicit instruction not to do it in most traditions, but it seems like such an unwise use of resources, unnecessary harm to one's own body, and affected. Then again, I'm just not a fan of "hip" Buddhism in general.
Obviously, I'm not referring to people who already have tattoos, so no offense demarous. If you plan to become a monk, you wouldn't be the first heavily tattooed one. Hope it works out for you if it's the path you choose!
"We do not embrace reason at the expense of emotion. We embrace it at the expense of self-deception."
-- Herbert Muschamp