A visual cheat-sheet for the 135 default keyboard shortcuts found in SketchUp Pro.
A — 2 point arc tool
C — Circle tool
Shift C — Circle tool - lock current inferences
E — Eraser tool
Alt E — Eraser tool - soften or smooth (use on edges to make adjacent faces appear curved)
Shift E — Eraser tool - hide
Alt Shift E — Eraser tool - unsoften or unsmooth
L — Line tool
Shift L — Line tool - lock in current inference direction
(arrows) L — Line tool - lock direction
M — Move tool
Alt M — Move tool - move a copy
Shift M — Move tool - hold down to lock in current inference direction
Ctrl M — Move tool - auto-fold (allow move even if it means adding extra edges and faces)
(arrows) M — Move tool - lock direction
F — Offset tool
O — Orbit tool
Alt O — Orbit tool - disable 'gravity-weighted' orbiting
Shift O — Orbit tool - activate pan tool
B — Paint bucket tool
Alt B — Paint bucket tool - fill material, paint all matching adjacent faces
Shift B — Paint bucket tool - replace material, paint all matching faces in the model
Shift B — Paint bucket tool - replace material, paint all matching faces in the model
Alt Shift B — Paint bucket tool - replace material on object, paint all matching faces on the same object
Ctrl B — Paint bucket tool - sample material
P — Push and pull tool
Alt P — Push and pull tool - push or pull a copy of the face, leaving original in place
R — Rectangle tool
Alt R — Rectangle tool - start drawing from center
Q — Rotate tool
Alt Q — Rotate tool - rotate a copy
S — Scale tool
Alt S — Scale tool - scale about center
Shift S — Scale tool - scale uniformly, don't distort
Space — Select tool
Alt Space — Select tool - add to selection
Shift — Select tool - add or subtract from selection
Alt Shift Space — Select tool - subtract from selection
T — Tape measure tool
Alt T — Tape measure tool - toggle create guide or measure only
(arrows) T — Tape measure tool - lock direction
Z — Zoom tool
Shift Z — Zoom tool - combine with click-drag mouse to change field of view