I've used redo once in the last two years or so. Parsing a file with a rather involved format I had several subs to handle specific sections; these sections did not have a closing token of any kind, so the subs had to get a token to find out that they don't recognize it and that their section is over. Rather than futzing it so I can "unget" a token, it seemed easier to just return the current one and redo in the main loop.

so:

while(<FILE>){
    if(/Foo/){
        $_ = foo();
        redo;
    }
    elsif {
     # do lots of other stuff
    }
}

sub foo {
    while(<FILE>){
        if(/something or other/){
             # so stuff
        }
        else {
            return $_;
        }
    }
}
[download]

Note that foo() doesn't see the line containing "Foo" nor did it need to in this case.

Worked well, certainly don't know if that's doing the Right Thing.