When sculpting I often want to switch between brushes. I find this a rather lengthy process. I have to open the sidebar and click on the icon and then click on the new brush I want to use. Is there a faster way to switch between brushes?

When sculpting I often want to switch between brushes. I find this a rather lengthy process. I have to open the sidebar and click on the icon and then click on the new brush I want to use. Is there a faster way to switch between brushes?

M = Mask Painting
K = Snake Hook Brush
Shift+C = Crease Brush
C = Clay Brush
Shift+T = Flatten/Contrast Brush
L = Layer Brush
G = Grab Brush
I = Inflate/Deflate Brush
P = Pinch/Magnify Brush
S = Smooth Brush
1 = Blob Brush
2 = Clay Brush
3 = Clay Strips Brush
4 = Crease Brush
5 = Fill/Deepen
6 = Flatten/Contrast Brush
7 = Grab Brush
8 = Inflate/Deflate
9 = Layer Brush
0 = Mask
Shift+1 = Nudge Brush
Shift+2 = Pinch/Magnify Brush
Shift+3 = Rotate
Shift+4 = Scrape/Peaks
Shift+5 = SculptDraw
Shift+6 = Smooth
Shift+7 = Snake Hook
Shift+8 = Thumb
Graphic below, slightly outdated. Twist was renamed Rotate and Shift+Number hotkeys re-assigned.
Current as of Blender 2.79a
There are letter shortcuts for most brushes, S for smooth, D for brush/draw, etc. as well as number shortcuts (1 for blob, 2 for brush, etc. Note that the number shortcuts depend on the order of the brushes in the menu, so 1 is always the first brush but necessarily blob)
For a full list, go to CtrlAltU> User Preferences > Input and search for "brush":

And then scroll down to the Sculpt section:

There are options (for which brush to select) available if you expand a shortcut entry:

You can easily create your own shortcuts by
Pressing Add New
Set the shortcut actuator options (mouse or keyboard, modifier keys, shortcut key, etc.)
Type in paint.brush_select as the operator.
Select Sculpt as the paint mode (note that it will be grayed out until you select it).
Select the sculpt tool.

Also note that the Smooth brush can be activated without switching to another brush by holding Shift.