Thich Nhat Hanh was noted for his devotion to the practice of walking meditation and mindful walking in general. An article that describes the practice and its connection to reverence for the earth can be found here: Thich Nhat Hanh on Walking Meditation
Ajahn Sucitto has an article on the practice of standing meditation that you can find here: Standing Meditation
Although meditation while lying down can be difficult because it can be hard to remain awake, it is one of the 4 recommended postures for meditation. That is especially true if you have physical issues that make sitting up straight painful. You can find a description of meditation while lying down here: Can You Meditate Lying Down? along with a description of a couple of different postures for meditating while lying down.