Validating HTML Input

[eluser]DennisP[/eluser]
So I've been developing with CodeIgniter for about a month and a half now. I really like it so far.

One thing that's kind of bugging me, is the lack of built in HTML validation. I don't mean XSS filtering and such, but just checking for closing HTML tags, stripping bad tags out, removing onmouseover="", etc.

Anyways, does anyone have any tips on how to do this? Is there a library someone has written to do this?

Thanks.