I will second the post on Messermeister. I got one that is 24 inches long. It holds three paring knives, three chef's knives, one bread knife a carving fork, a utility slicer and kitchen scissors as well as my AG Russel Honcho knife.
Your knives will never fall off, believe me.
There is a knife shop here in San Francisco, We Be Knives, must have about 150 of these magnetic holders to display knives on their walls, all lined up.
I got mine at a local kitchen supply shop for cheap.