FYI ... I flew stand-by on both legs of my Sunday afternoon ROC-JFK-RSW flight ... I had booked the later set of flights because it was significantly cheaper, but less convienent. I checked in at the counter (not online) and they put me stand by on both and gave me the option to pay the $25 to be confirmed or take my chances for free (i chose the free option) ... ended up having no trouble on either leg (ROC-JFK had 6 free seats, JFK-RSW was maybe 60% full), even checked a bag which showed up without problems as well. So it should be more than possible, just ask at the counter or the gate.