I've been sucking down tutorials and I almost choked on this tip. I snagged it as an aside in the first tutorial by Jen Caputo on Digital Scrapbooking TV. I had some issues with Quick Time, but I'm a die hard PC user. Anyway, I always thought there ought to be some way to just select the item on the layer, without all that Magic Wand or Magnetic Lasso nonsense.
Duh. Move your mouse pointer to the icon in the layers palette. Control+click and the item on that layer will be selected. Instant marching ants neatly all around it. You don't even have to have the layer selected.
I already knew that to deselect something you can hit Control+D.
As Ron Weazley would say, "Brilliant!"