Pick the right variable and function names and half the commenting is already done.
One of my favorite techniques is to write pseudocode as comments and work out the basic mechanics there then write the actual code in between the pseudocode comments. It's never perfect but it works.
I dunno what you call esoteric but for me bit shifting and logic are not that. The triple XOR was neat but yes, that one really deserved comments! If you don't like & and | then use AND and OR even if you have to #define them.
The part I like most about Arduino is that I don't have to deal with an OS on the target machine.