Probably not the kind of tool you are asking about, but I made a pair of woodworking planes that cut a quarter inch wide, quarter inch deep groove a quarter of an inch from the edge of a board. This operation is commonly needed for drawer bottoms and raised paneling. Two symmetric planes are needed so that you can always work with the rising grain of the wood.

You can buy adjustable grooving planes and old molding planes that will do this, but it was fun (and much cheaper) to make my own pair.