I love suspension trainers! I use them in almost ALL of my Circuit Training classes!
They provide a full body workout and all it takes is your own body weight!
There are many different kinds out there in the fitness world I have used the TRX brand (probably the most popular) and now at the gym we have a Lifeline USA Jungle Gym XT. Both of these work great, and I am sure there are many other great ones out there too!
Demonstrated below is a Single Leg Lunge:
Step 1: Facing away from the suspension trainer, use just one of the straps for one of your feet:
After securing one of your feet in the strap, you will have to hop your front foot forward a bit.
Step 2: Bend the knee of your front leg and push back into a lunge with your other leg:
Keep your head up, back straight, and your core tight, engaging multiple muscles!