Of course, for low currents, you can always a LM334 + resistor.
If you require a zero TEMPCO source, an additional diode and resistor as shown in data sheet.

 

I keep several of both the LM317 & LM317L in my stock. I had to put a 50mA constant current source circuit together to align and calibrate my Simpson 260 Series 5 meter. Not much of a load so it might be interesting to try using the L next time as it's rated for 100mA but for the Power Dissipation the spec reads "Internally Limited" so not sure just what the L can do. If not, then the big LM317 will do... Or, get a power load tester and push one to failure to see just what it can do.

 

you can always a LM334 + resistor.

I looked at the LM334 but it was pretty limited both in current and power dissipation. Might get a few from AliX to play with and see just what they can do.

 

but for the Power Dissipation the spec reads "Internally Limited" so not sure just what the L can do.

When the internal temperate of the device gets too high, it will reduce the current to protect itself.
That's part of what makes the LM317 nearly bullet proof.

 

Yes, temp limited and short circuit protected but wonder just how many mA or mW it can handle until overtemp? Just ordered an up to 5A power load test module so I guess I'll find out... Only does 0.01A scaling though so in 10s of mA but says 1% accuracy if not BS. We will see...

 

wonder just how many mA or mW it can handle until overtemp?

it's determined by the power it has to dissipate, the thermal resistance of the device junction to air, and the ambient air temperature.

Below is the thermal resistance for various packages along with the maximum allowed junction temperature (which is likely around where it starts to thermal limit).: