- Pencil
B
- Erase
E
- Default Foregroud/Background Colors
D
- Toggle Quick Mask
X
- Hue/Saturation
Ctrl + U
- Color Balance
Ctrl + B
- Image Size
Alt + Ctrl + I
- Canvas Size
Alt + Ctrl + C
- Change Screen Mode
F
- Actions
F9
- Brush
F5
- Info
F8
- Layers
F7
- Tools -> Toggle Brush Pressure Controls Opacity
N
- Application Menus -> Image Rotation -> Flip Canvas Horizontal
Ctrl + .