Suspension Training (a bodyweight fitness system that uses ropes and webbing) is a growing trend in the fitness industry. You have probably seen people at the gym doing all sorts of strange looking exercises including pushups and knee tucks with the feet suspended in the air. TRX is the most well known brand, but other manufacturers are rolling out their own versions. It has the advantage of being lightweight and portable, so it is a great piece of equipment for those who travel.
This type of training can improve strength as well as balance and flexibility. It is getting a lot of publicity as the latest thing in core training; to do it right you must use your core to stabilize. Suspension workouts consist of either hanging the legs in the straps, or leaning back while gripping the straps and then performing a variety of moves. The workouts fit right in with the current trend of functional fitness, as the muscles are trained as a group, rather than individually.
However, despite the hype, this type of workout is not for everyone. If you do not have adequate core strength, it is easy to go out of alignment and risk injury. Those with high blood pressure or those on beta-blockers may need to avoid the inverted postures. The instability of the straps can also cause problems for those with joint or back issues, and the pushup position required for many of the exercises can put stress on the wrist.
If you are in good shape (or at least have a qualified safe instructor), suspension training is a versatile effective addition to your training.