Have you heard of Jet America? They are a new airline (they are a dba of Sun America) and their deal is that they offer $9 each way fares. They guarantee 9 seats at $9 for each flight (plus a $5 convenience fee for booking online).
I checked a flight in August. There are no flight time options for the route I selected and the seats currently available are at rate of $29 each not including fees. Still, even with fees (includes online booking), this round trip flight was under $90.
However, there were other add on fees for some services (all each way) - if you call the call center to book the flight, there is a $10 convenience charge, baggage fee is $20, a minor flying unaccompanied is $50, reserving a seat is $10, etc., so I am sure that it could add up to a more standard feeling fare quickly - but let's be honest, a lot of other airlines have a whole menu of fees as well. But, if you don't need all the extras and live where they fly, it could still be a pretty good deal.
Right now, they fly between a number of smaller airports (and Newark?) including: Toledo, South Bend, Minneapolis, Lansing, Orlando and Newark.
Flights start in July and right now, you can book through October.
How long will they sustain? Wasn't it just a few months ago that another airline with a similar pricing deal went under.