The Heavy Bag - a great tool to execute techniques at full power with out having to worry about hurting a training partner. It's also great for working your chops at your own pace and paying attention to detail.
Of course, it also great for conditioning - take a simple movement and repeat for x amount of reps or time. One of my favourite, and a standard in most gyms, is throw hard knees against the bag. This allows you to work on power, balance, speed and cardio conditioning. Here's a few tips to help your practice.
Dan Slobodin -