An Out Of The Ordinary Hotlinking Question - Stopping Hotlinking From OTHER websites?

[rokked]

For instance:

I was thinking maybe even something could be done with a simple word filter. Like, anything contained within an tag would somehow be scoured, and if in between the tags the words "imageshack", "photobucket", "geekfag", etc were not contained anywhere, they url would just get wordfiltered into **************. That way, you could write-up a safe list of hosting sites, and manually add them to the code when needed.

Is something like that even possible? Or is there any more information on complex wordfilters? I think it would be all we'd need to do.