Right now strip_tags() is a great function. You specify a string and the tags you want to keep. What I would like to see is another argument in strip tags so that you could tell it to keep or remove the tags you specify. I saw bug #5976 that had something to do with this very thought, but this extends the idea further. For example, if I have a string full of HTML and I want to remove all <script> and <meta> tags but keep the rest, I could do something like 

strip_tags($string, '<meta><script>', true);

That boolean value of true as the third argument would tell the strip_tags() function to remove the tags specified. Without that, it defaults to the way it is now and removes all but those tags. I think this would be a very handy thing to have in PHP. Thanks.