My dad used to do this before he got into building databases, but it was 20 odd years ago so obviously it's very different now with computers being everywhere.
OTOH I have just got a little work arranged via family, typing somebody's book manuscript, as they don't have a computer. I'm really loving it (aside from the extra money of course, which is very useful as I can only physically manage PT in my day job).
But I'm not sure if there would be any point pursuing further work like this? I wouldn't know where to start, even if it were worth starting!
Grateful for any thoughts! :)