This is a quickie. I've actually got a few videos with some slightly more interesting (I think) tutorials that I'll post up later.
I hate the +/- Avg node in Maya for adding two numbers. It usually takes some fussing to get it work correctly (I think it might even be buggy, or at least poorly conceived). So I usually use the script editor on the bottom left corner to create an "addDoubleLinear" node. This is more straightforward . . . takes two scalar inputs adds em and gives a result. Just type "createNode addDoubleLinear -n *name it what you want*".
The only problem is that this add node doesn't show up in the hypershade, which is where I do most of my connections. So here's a better way. . .
Create the ADL node like you'd create a mult/div node or other utilities with MEL. Instead of "createNode", use "shadingNode -asUtility addDoubleLinear".
This creates the ADL as a utility which shows up in the HS window under the Utility tab. Now you can finally sleep at night!