Profanity Filter

I'm trying to find or create a profanity / swear filter. I did my foot work / searched around the site and it doesn't seem like one exists. I'm very well versed in PHP and fairly familiar with Elgg. I'm having trouble trying to figure out how to hook all input (or output) to filter out the text.

I know how to do it with modifications to the core, but I obviously try to avoid core modification whenever possible. Plus I'd like to create a stand-alone profanity filter module that I could share with the community.

The only option I've come up with so far would be to override the view/outputs and filter it there, but this feels a bit to hack-like. Is there any way to hook all input and check it? OR any other alternative idea would be appreciated.

thanks in advance.