Breakthrough at Magic Lantern, imho this elevates it to a must-have and makes Canon look really stupid: They at last figured out what the digic registers having to do with iso are, and by fine-tuning them your camera now gets an additional 1/3-1/2 stop of dynamic range,
no strings attached. Just use +1/3 stop of ec (ML also has ec in m mode, just like the new 1dx fw) and you're done.
This means that for example on 5d3, iso 800 with ML has more dynamic range than iso 100 with Canon :-> ... and at high iso you're getting 7% more dr which is nothing to sneeze at, esp. since it builds upon Canon's advantage vs. Nikon: d800@6400 = ~8.3 & 5d3@6400 = ~9.4 ev making good ol' Canon the superior sensor for low light high contrast shooting, esp. the newer 6d.
isos = [ 100 200 400 800 1600 3200 6400 12800 ];
dr = [ 10.989 10.928 10.799 10.594 10.153 9.521 8.584 7.778 ];
dr_tweak = [ 11.371 11.334 11.239 11.028 10.598 10.017 9.131 8.360 ];
Read all about it here, test modules are about to be out, next coming to a nightly build near you! Here's the dev thread if you want to follow the development: http://www.magiclantern.fm/forum/index.php?topic=10111.msg97780#msg97780
If you feel exposure challenged, you can use the ettr module to automatically set the exposure so it covers exactly the dynamic range of the scene with optimum snr :-)
Edit: Updated 5d3 numbers & changed topic, keeping the same(!) iso value the general improvement is more like 1/3ev and not 1/2ev like first reported (it's wip, people!) because the ML iso trick lowers the nominal iso a bit.