Backup revisited

 From:  ggagnon
Hi Michael,
I save often while I work but I wish now I could get back to a version I made a few saves away.
Undo is not an option since I left the program and it is when I came back to it that I realize I had accidentally deleted some part of my work.

What is the usual way to deal with this kind of situation?
One way could be to create a new version every time a save is done. Keeping a number of past saves on disk. That would be really handy today.