Piriformis syndrome: Sciatic pain relief stretches and exercises:

This tutorial includes following sciatic pain relief stretches and exercises: 
- buttocks stretch 
- supine piriformis stretch - hip and knee stretching
- piriformis muscle stretch - supine
- hamstring stretches with both legs 
- hamstring stretches with one leg stretched out 
- hamstrings stretching with leg raised 

Piriformis syndrome is a neuromuscular disorder that occurs when the sciatic nerve is compressed or otherwise irritated by the piriformis muscle causing pain, tingling and numbness in the buttocks and along the path of the sciatic nerve descending down the lower thigh and into the leg. (Wikipedia, Piriformis syndrome)