The BOSU Balance Trainer is good for a variety of functional workouts for the entire body.
http://AskTheTrainer.com/bosu-ball-exercises.html
If you don't know whether you should be doing lower back exercises you should check out the following article:
http://AskTheTrainer.com/best-lower-back-exercises.html
If you have any problems with muscle or joint pain you may have muscle imbalances and resulting posture problems.
It is very important you read the following:
http://AskTheTrainer.com/posture-problems.html
