tools for "shrinking" a DVD

I came across these tools, haven't tried them yet myself, but I am definitely going to, and at least XDVDShrink must be quite reasonable, as it has pretty good ratings resp. weekly download figures at sourceforge:

• XDVDShrink
• vamps

Both are available on the Packman Repository for openSUSE 11.2, which I use directly with yast; there are also sister repositories for other Linux distributions on that site.
I definitely need to back up and shrink my and my friends' very precious DVDs like Peter Pan, Toy Story, etc.