Here is a video of Brad going through a lunge workout on the Powertec Compact Leg Sled. This is a great way to recruit more muscle groups than performing a traditional leg press.
I was never a huge fan of lunges and used to stick mainly to squats thinking these were the best for my legs. Squats are great but it is also good for the mind and body to incorporate a bit of variety into your weight training. Since lunges were a favourite with the women I also thought they were a bit soft.
The lunge workout on the Powertec Compact Leg Sled is actually quite brutal. I just keep going from leg to leg until I run out of juice. Then switch to the traditional press position and continue until the legs are absolutely hammered. I find I can really push harder and isolate the legs the better on the Powertec Leg Sled than with traditional lunges. I usually do traditional lunges with dumbbells and I find once that I start to fatigue my form gets a bit sloppy. The Powertec Leg Sled just lets you concentrate on driving with the legs.