none of the girls in my chapter have our letters or anything DO related tattooed on themselves, although it's a big thing to do among the fraternities on our campus.

As far as I know, we don't have really any steadfast rules about tattoos/piercings - I don't know if we'd bid somebody that had 100 tattoos on her, but generally, I think our rule is, as long as it's tasteful and can be covered up for pictures, etc. go for it. A lot of girls in my chapter have tongue or navel piercings, but that's kind of the same thing - not terribly visible.