This nice little iPhone app I’ve found allows you to setup workouts and track your progress. Much like the people you see at the gym with low-tech clip-boards, you can track your progress on each exercise/piece of equipment and still listen to music all while not carrying around a clip board (with an iPhone or iPod Touch).
This app gives you some basic advice on working out. It also allows you to create workouts by muscle type or whatever you deem important and track your weight and reps by exercise. It also has a timer to track resting time (although I haven’t gotten that feature to work out yet.) It’s a good all around gym notebook from my experience.