There are multiple ways to join two pieces of wood that range from butt joints to rabbet joints. Most of these connections connect two perpendicular boards, for instance the sides of a drawer. However, many applications require boards to be parallel to each other, such as when making a table top. These situations need the boards to be precisely aligned. There are a number of ways to join these pieces, including using splines and the drill and dowel method.
When making table tops in the past I liked using a biscuit cutter and oval biscuits to both align the planks and to gain a bit of structural strength. The biscuit cutter makes semi-oval cuts in two adjoining pieces of wood in which an oval shaped biscuit is inserted. These biscuits can be made of wood, metal, or plastic and are similar to but not as strong as a traditional mortise and tenon joint. Although this technology is great I think I have found a gadget that does the standard biscuit cutter one better. That tool is the Festool Domino Joiner.
The advantage of the Domino Joiner is that it makes a precision cut for a wooden “Domino.” These wood plugs are significantly thicker than a standard biscuit, and therefore stronger. The Domino Joiner easily controls the size, angle (fence tilt), and plunge depth of the cut allowing it to be useful in a variety of situations. In addition, the joiner can make cuts for other types of tenons, such as metal strips that use screws. See the photos below.