One of my favorite keyboard shortcuts in Photoshop and Photoshop Elements are to change blend mode from keyboard. You can cycle through blend modes if you want or to apply specific blend mode directly from keyboard without to click triangle next to drop down list with blend modes each and every time.
How to change layer blend mode
To change layer blend mode in Photoshop and Photoshop Elements you must have active any tool which does not offer blend mode at tool options (just below menus), for example Selection tool (V), Marquee (M), Shape tool (U) and so on.To cycle through blend modes (with layer to which you want to apply blend mode selected on Layers palette) press Shift + (+) to apply next blend mode or Shift + (-) to apply previous blend mode. To apply specific blend mode add and Alt key and press letter, for example to apply Multiply blend mode press Shift + Alt + M, to apply Screen blend mode press Shift + Alt + S, Overlay blend mode is asociated with letter O and Soft Light with F, Color with letter C and Luminosity with Y (Shift + Alt + Y). To go back to Normal blend mode press Shift + Alt + N.