https://blendermarket.com/products/uv-flow

UV Flow aims to make UV unwrapping in Blender fast and, even more shockingly, actually fun. It does this by adding an entirely new active tool to Blender’s toolbar, called Cut UV, which allows you to edit seams with ease.  The controls are intuitive and there is a pre-selection highlight to help you never miss a cut. Simply click to mark seams, double click to mark loops (which stop at other seams!!), click and drag to draw seams, hold alt during any of those actions to clear seams, and double click on faces to select islands.