This page gives an overview of the default Unity Hotkeys. You can also download a PDF of the table for Windows and MacOSX. Where a command has CTRL/CMD as part of the keystroke, this indicates that the Control key should be used on Windows and the Command key on MacOSX.
The Mac trackpad also has a number of shortcuts for navigating the Scene view. See Scene view navigation to learn more about these.
Tools
Keystroke
Command
Q
Pan
W
Move
E
Rotate
R
Scale
T
Rect Tool
Z
Pivot Mode toggle
X
Pivot Rotation Toggle
V
Vertex Snap
CTRL/CMD+LMB
Snap
GameObject
CTRL/CMD+SHIFT+N
New empty game object
ALT+SHIFT+N
New empty child to selected game object
CTRL/CMD+ALT+F
Move to view
CTRL/CMD+SHIFT+F
Align with view
SHIFT+F or double-F
Locks the scene view camera to the selected GameObject