Here is my hand picked selection of NodeGroups i've created over the past 2-3 years. There's everything, from simple little Tools, Materials, UberShaders to Compositing. Some are made quickly, on some i spent countless hours.
With this first release i've put together some information about every NodeGroup. Not too much, but mainly what the NodeGroup is supposed to do. I think it's important to get a quick start on them, cause really, some of them might seem confusing (even for me ;-) by just looking at it.
I've taken quite some time to re-check everything, set usable and good defaults and to make them as easy as possible.
All of those NodeGroups are made by me, with the exception of the CondFresnel in the Metal-Kn.
I always try to not let them break energy conservation - so they should be safe to use in any circumstances.
More Info here.