Redstone line going up a slab acts as a dot, powering mechanism components next to it, even though it appears to not be pointed at them.

Two pieces of redstone dust placed next to each other, one of them being one block above on an upside-down slab. Lower piece of redstone dust appears to be a line going in a direction of a slab, but when powered acts as a dot, activating blocks and mechanism components placed next to it.

Screenshot: http://imgur.com/YOWt1iT