I think the only changes I would make involve a few trivial simplifications:

sub list {
    my @words = split( /\s+/, $_[0] );
    my $lastword = $#words;
    for my $i (1..$lastword) {
        push @words, map { join " ", @words[$_..$_+$i] } (0..$lastword
+-$i);
    }
    return @words;
}
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Notes:

• Assuming that $/ has its default value, splitting on white-space makes "chomp" unnecessary
• Your map-within-foreach covers everything, including the "substring" containing all input words
• You can eliminate most of your temporary storage variables, but ...
• ... it's important not to use "$#array" inside a loop when altering the size of @array in the loop (unless you're doing something different from this case, and you really know what you're doing)

(update: fixed  @_[0] --> $_[0] in first line of sub -- and this could just as well have been "shift".)