Well, if you are looking for leg exercises and you do not want to go to a gym, nothing can beat skipping the rope. Here is what I found on Wikipedia about skipping- Jumping rope is an activity not only suited for competition or recreation, but also for a cardiovascular workout, similar to jogging or bicycle riding. This aerobic exercise can achieve a “burn rate” of up to 700 calories per hour of vigorous activity, with about 0.1 calories consumed per jump. Ten minutes of jumping rope is roughly the equivalent of running an eight-minute mile. Jumping rope for 15–20 minutes is enough to burn off the calories from a candy bar.
Jumping rope can avoid the knee damage which may occur during running, since the impact of each jump or step is absorbed by both legs. Jumping rope also helps strengthen the arms and shoulders. This combination of an aerobic workout and coordination-building footwork has made jumping rope a popular form of exercise for athletes, especially boxers and wrestlers. Individuals or groups can participate in the exercise, and learning proper jump rope technique is relatively simple compared to many other athletic activities. The exercise is also appropriate for a wide range of ages and fitness levels. Jumping rope is particularly effective in an aerobic routine combined with other activities, such as walking, biking, or running.