Hentai stuff---yeah, take some precautions.
General nudity---nah, don't worry.

Why?  Well, consider what kind of anime the nude 
scenes are coming from.  Treat the visitors to 
your site just like a video store might treat 
them.  If the scenes come from something hardcore 
that might be kept from minors, then be careful.  
But if it comes from something that is readily 
available and has probably already been viewed by 
a wide audience, then assume it's okay.

Does that make sense?  ^_^

JP