I perform body-weight exercises and so far had something to progress to without requiring weights. I am now able to do 8-12 reps of Pistol Squats. To strengthen my legs further is there any other more challenging form of leg exercises that I can do without using weights, or have I reached the limit of body-weights in my case?
You can always increase the time you are doing the exercise, increasing the time under tension. In addition to it, you can also do the same exercises with "holds". For example, you can stay in pistol squat deep position for 15 seconds, and do 8-12 reps afterwards, it will be harder to do.
Apparently Shrimp Squat and Advanced Shrimp Squat seems to be more difficult that Pistol Squats.