Sprockets for hub gears

In a remarkable show of cooperation, most hub gears have compatible fittings for their sprockets. The exceptions are:

Rohloff's Speedhub 500/14
The Speedhub 500/14 sprockets are available in 15T, 16T (standard) and 17T, which are reversible to double their lifespan; and a 13T dished sprocket that has a 58mm chainline and is non-reversible. They are all for 3/32" chain and screw onto the hub.
Sturmey-Archer's 8-speeds
which have a much larger driver (and corresponding larger hole in the centre of the sprocket). They are available in 23 & 25 teeth, 3/32" or 1/8" and 19T 3/32" only. They are all dished.
SRAM i-motion 9-speed
These are available in 18-22T flat and have four splines compared with the standard which has three.

Availability of "standard" sprockets

Thickness/in	Dished?	Teeth
Thickness/in	Dished?	13	14	15	16	17	18	19	20	21	22	23	24
3/32	Flat			H	A		R
3/32	Dished				H	A	ARH	ARH	RH	RH	ARH	H	R
1/8	Flat	A	A	A	AR	AR	R	A
1/8	Dished				R	AR	AR	AR	AR	AR	AR		R

Key:

A = Sturmey Archer
R = SRAM
H = Shimano

DIY sprockets

With a little modification, a Shimano freehub sprocket can be used on a standard fit driver. The major diameter of the spline is correct, but a freehub sprocket has nine splines. Simply grind off six of the splines and reduce the width and depth of the remaining three until it fits.

Chain line adjustment

Your chainline can be affected by:

Whether the sprocket is flat or dished - The smaller sprockets are generally flat, the larger ones are tend to be dished, and the mid-sized available in both shapes.
If dished, which way around it is mounted
If dished, who manufactured it - SRAM's sprockets are dished by 3mm, Shimano's by 2.5mm
Thickness - the chainline of a 3/32" sprocket will be 1/64" (0.4mm) further inboard than a 1/8" sprocket unless it has been designed to allow for this.

Thickness / inch	Dished?	Manufacturer	Change in chainline / mm
1/8	Outwards	SRAM	3.4
3/32	Outwards	SRAM	3
3/32	Outwards	Shimano	2.5
1/8	No	-	0.4
3/32	No	-	0
3/32	Inwards	Shimano	-2.5
1/8	Inwards	SRAM	-2.6
3/32	Inwards	SRAM	-3