There's a mint to be made here or at least a crazy startup. Okay, so I have this boring email to, lets say, a girl I want to impress. I quickly forward it to the "witty people company" which is just a bunch of out of work writers and comedians sitting in front of computers. They spice up my email and charge me a small amount like a dollar or two or so. I get the email back in few minutes and incorporate the changes.

As long as they dont keep using the same gags or cut&paste it should work out. Perhaps with a guarantee for originality. A situation where someone gets four emails with the same joke or humorous observation and figures out you've got a ghost-writer shouldn't happen.