local $SIG{PIPE} = 'IGNORE';
    open PAGER, '|'.($ENV{PAGER} || 'less')
      or die "Can't spawn pager: $!\n";
    while (something) {
        print PAGER something_else;
    }
    close PAGER;
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The (temporary) assignment to $SIG{PIPE} keeps your program from dying if the pager quits early. If you're concerned about wasting time generating useless data, you may want to add this refinement:

    select PAGER;
    $| = 1;
    while (something) {
        print something_else
          or last;
    }
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Remember, tool use is one of the things that make us human. :-)

UPDATE:Thanks to agoth for the bug fix. And yes, tye, I know that Windows has a "more" command. But it's so hostile that I never use it. There is a Windows port of "less", anyway.

    -- Chip Salzenberg, Free-Floating Agent of Chaos

But

open PAGER, ($ENV{PAGER} || 'less') . '|' or die "blah $!";
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Doesn't open a pipe to the pager, least not on my system? (main::PAGER only opened for input), Am I missing something? But thanks for leading me to:

open PAGER, ('|' . $ENV{PAGER}) or die "blah $!";
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Correct. And that should be

$ENV{PAGER} || 'more'
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so that it works on Windows (contrary to the original proposers claim) and on many other systems that may not have 'less' installed.

Maybe Term::Screen is what he's looking for. Check this:
Term::Screen POD in HTML

$SIG{INT} = sub {
  print "recieved SIGINT. Help!!\n";
}
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