Valujet actually started up again for a while after the FAA shut them down. It didn't last long. They hit rock bottom, and then they bought out AirTran. As I understand it, they needed to get a change of image fast, so they "bought" AirTran for its name and pasted the AirTran logo on all their planes. Valujet is still around, but under a different image. The 737-200s in AirTran came from the original AirTran, and the DC-9s are all ex-Valujet.
It's sort of a sneaky trick, but it worked and AirTran is booming now.