I have 2 plastic storage drawer units. I wanted the thread spools to stay in place, so I lined the bottom of the drawers with peg board and then glued golf tees into the holes. It works great. I had to have my dad drill the holes slightly larger to accommodate the size of the golf tee heads (we left one hole between each of the golf tees). It makes it easy to just open the drawer and see what colors you have.
To keep the thread from unraveling off the spools, I tape the ends to the thread with a snip of the 1/4" tape they sell at JoAnn's to mark 1/4" on your quilting projects. It doesn't seem to gum up the thread (it's designed not to gum up the quilt projects) and seems to work fairly well - although the adhesive does dry out after a few months. It does seem to keep my thread drawers nice and neat though!