Yuri mentioned: "Like a harmless astronomy site that gets blocked because it talks about stars visible to the _naked_ eye. A good content filter might give weightings to words, in relation to proximity to other words. eg "naked eye" and "naked flame" are scientific web pages, while "naked butts" mite be filtered out."
Dans Guardian does exactly what you suggest, it comes with a prepared 'weighted phrase list', which you can edit to your hearts content. Web pages containing the phrase 'naked eye' or the word 'sex' for example will not get filtered the words have to occur in conjunction with other naughty words and a page containing 'naked butts' certainly does get filtered. Check it out. On the other hand Dans Guardian doesn't do image analysis looking for 'too many pink bits' (you'd need quite a bit of grunt to do that fast enough). A page that was just a picture with no naughty words would slip past DG, so there's still an opportunity for you there Yuri. You can of course still blacklist such pages manually by site or URL .
