The next thing they want is for someone to be able to "approve" a page online. For this I am envisioning an "approve" tab/button along the top that adds a signature line (I'm pretty sure I could figure out how to do this).
I'd like the signature line (~~~~) to be put on the "Discussion" page, or maybe an "approval" page, but I'd also like this approval page to be non-deletable... can only add text to it. (This part I'm definitely not sure how to do. I do see the '+' tab on our discussion pages though.)
Take a look at the FlaggedRevs extension - it doesn't do exactly what you're saying, but it's close. (I think the extension is still in beta testing, though, so be warned.)