Cmd-L | Automatically typeset using the correct engine.
Cmd-T | Typeset using just LaTeX.
Cmd-B | Typeset and run BibTeX.
Cmd-I | Typeset and run MakeIndex.
Shift-Cmd-I | Typeset and run BibTeX followed by MakeIndex.
Cmd-K | Delete the temporary directory with intermediate files produced during a typeset.
Cmd-. | Abort a typeset operation.
Cmd-/ | Comment the selected block of LaTeX source.
Cmd-/ | Un-comment the selected block of LaTeX source.
Cmd-1 | Toggle the outline view.
Cmd-2 | Show only the editor and not the output.
Cmd-3 | Show both the editor and the output side-by-side.
Cmd-4 | Show the output (PDF) only.
Cmd-J | Switch the focus between the editor and the output pane.
Cmd-8 | Show the PDF in the output pane, when available.
Cmd-9 | Show the error log in the output pane, when there are errors or warnings.
Shift-Cmd-= | PDF zoom in. (Also works with Cmd-=.)
Shift-Cmd-- | PDF zoom out.
Cmd-R | Reveal PDF in Finder.
Cmd-E | Email PDF.
Shift-Cmd-F | Global Search.

Note that in the above, Cmd-X means simultaneously pressing the command key ⌘ and the key X.