Never thought I'd see "commuter flights" and USA 3000 in the same subject line.

These appear to be mainly re-positioning flights. Not too many other airlines have tried a red-eye between PIT and PHL, or from DTW to ORD. And some of these fares don't seem to be much cheaper than SWA, which offers...you know...day time departures, among other amenities.

Still, it's kind of fun to play around and see what weird options they come up with. It's probably a chance to book a flight where you might literally be the only passenger on an A320.

Edit to add: I did find some daytime departures, such as PHL-PIT at 4:20 p.m. for $49 + tax. Not too bad, assuming you want to fly on the handful of days it's offered. But the return flights PIT - PHL are at 12:30 a.m. The annoying thing is that these flights are not included on the .pdf timetable on their website, so you kind of have to fish around.