When you need to swap knives quickly during a cooking project, a magnetic knife block can be your best friend. If you want to make your own, it's easy to do with some wood and hard drive magnets.
Instructables user tzny shared his process for building this attractive knife block. He cut two identical planks of poplar, and used wood glue to attach wooden spacers to the edges of one of them. He then mounted his hard drive magnets to the underside of one plank, and closed the block off with the other plank. If you don't have any old hard drives handy, any strong magnet should do as long as your wood is thin enough.