As a dancer, I have always done a lot of squats and lunges. The first time I performed the single leg squats on the TRX my legs were on FIRE!  I became addicted!  I enjoy the fact that I can use more range of motion without any strain on my knees at all.  I also enjoy doing some of my ballet workout exercises which would traditionally be performed while holding onto a ballet bar. With a light hold on the handles (single handle mode) I have just enough support to perform my pliers.  The TRX  is also an amazing flexibility tool, will you eventually have a DVD program for stretching?  Thanks

On some other thread, i forget which, Frazer said that they are releasing a 'Flexibility' DVD in their series, and that will focus on stretched that can be performed using the TRX.

Another option while you wait is to check out the pilates poster that is currently available.  I haven't tried it myself, but from the description and picture, it looks like it offers a few good exercises for increasing flexibility and strength; I imagine it would mesh well with your current ballet exercises!