I grabbed a small cardboard box (smaller than a shoebox), cut a hole in each end, and coiled all the extra length inside. So the only cables you see are the ones that enter (and leave) this neat littl cardboard box (actually the box is tucked under the entertainment unit) and the cable are all tied together and exactly the right lengths are exposed.

Simple and effective, and zero cost.

You can also coil power leads like this, but obviously don’t put the power board in there!