Useful keyboard shortcuts in the finder I didn't know of.

Move up the hierarchy: Cmd + Cursor Up

Open a file/folder: Cmd + O (like "open") or Cmd + Cursor Down

Pressing Cmd while Drag'n'Dropping files: Moving files instead of copying them (quite useful, since there is no Edit→Copy in Finder)

Thanks to: Robert Buluschek, Florian Hillebrand, John Flury.