I have had a couple lucid dreams, but no dreams where I have achieved 100% lucidity. (The point where you can create or do anything that your mind dictaes to the dream.) Gravity is never totally eliminated in my dreams, but I have done trippy things in dreams such as pull the stars down towards me, and cause a rock to grow eyes a nose and a mouth. The trick is all in being able to notice when you are in a dream. Also, a tip for making a lucid dream last longer and become stronger is to spin around in the dream, or rub your hands together in the dream. Try it next time you are in a lucid dream, I guarantee it will have an effect.

EDIT: In all of my dreams I have the sensation of touch and feeling, see colour and have hearing. My problem is thinking that my dreams are reality. Usually I think all my dreams are real life until I wake up. When you realize you are in a dream, a world of possibilities opens up for you. I love the feeling of realizing you are in a dream.