This morning, one of my Introduction to Photoshop CS4 students asked me how to center her text on the canvas. After I pushed Illustrator's "Align to Artboard" command out of my head, I couldn't come up with a really quick and easy technique.
Turns out there is one: just select the text layer and the background layer in the Layers panel, and then pick the Align Center button on the Options bar. (The text aligns to the canvas-wide background layer.)
Seventeen years of teaching Photoshop and I never knew!