Tape measures went digital some time ago, but those were laser-based and only performed linear measurements. The Rollbot from iGaging uses a simple serrated ring around its circular edge to roll like a wheel across any flat, curved, or irregular surface with the measurement appearing in a digital display on the front of the tool.
The Rollbot can easily measure linear dimensions like the length of a board. But, it can also calculate the square inches of a board face, or calculate board feet (the way sawmills price lumber with a bd ft = 1'x1'x1"), or calculate the round area and diameter of cylinders such as tree trunks or turning blanks by measuring the circumference. Plus, it can do corner and inside measurements such as from one end of a bookshelf to the other by merely adding its dimension to the measurement it rolls. The Rollbot can handle any size up to 144", and measure at up to about 18 feet per second.
Loaded with great features: