How To: Sew Piping - Tutorial
Couching is simply sewing a heavy thread in place with a finer thread. It works beautifully by machine as well. I use a zigzag stitch to secure the heavy thread in place. And, if you have a cording foot— the foot guides the thread as you sew.
How to Take in your Jeans Waist - Step by Step Tutorial (this one is actually done 'correctly' at the waistband, instead of the lazy way)