I have to disagree with many comments. First of all nudity is not necessarily erotism or pornography. And nudity is not shameful or sick. Hiding each and every nude pictures from kids is just as bad as showing them porn. Don't classify artistic nude as something shameful. That site provides basic safety for child, you cannot do more without implementing codes... and cost. The rest lies in parent responsibility and education !
I have to agree there's a lot of nude pictures, fortunately most of them are of good taste and artistic value.