Although it's all done unglamorously undercover, companies, Big Shots, VIPs and others who need help with a book introduction, speech, or similar have been known to ask me to help out.
Unfortunately, I can't give you any names (please, don't even ask) but, as an example, it might have been a page written by a celebrity for a children's annual (when he/she doesn't have the time to do it); it might be for someone very important who is contributing the forward to a book (when he/she doesn't have the time to do it); it might be tidying up a speech for a big launch (when he/she doesn't have the time to…well you get the idea now). It could also be cleaning up or putting some polish on web content. It might be editing someone's book.
If you need this type of assistance, you know where to find me.