Here's a little idea I'm throwing into the ring for flaming:
How about if any questions with the word "Arduino" in the title automatically get migrated instantly to the Arduino SE? Even better, they never appear on EE, but go straight to A.SE...?
Or even better, you could set up your filters to ignore questions tagged arduino.
There are two broad classes of questions on EE.SE that have the arduino tag.
The first class is about an issue that is specific to the Arduino HW/SW environment.
The second class is about a more general EE (or embedded systems) issue that just happens to arise in the context of an Arduino project.
As a moderator, I try to figure out which class a new question falls into, and migrate the former to Arduino.SE, and keep the latter in EE.SE.
Aggressive migration of Arduino question was proposed and hotly debated the moment Arduino.SE went into public beta. See comments in this thread (if you haven't seen it already).
There is a bigger long term underlying problem. Questions older than 60 days can not be migrated. All these old threads act like bait for search engines, which attract ardweenie traffic. There's little we can do about that old bait.
Here's an example: old thread itself, related meta thread. Best viewed with 10k visibility.
At the moment of writing, Arduino.SE has got 650 threads, EE.SE and StackOverflow has got 2,800 and 4,200 threads tagged arduino , respectively. StackOverflow gets the greatest number of new Arduino questions per day.
Users who have accounts on both Arduino.SE and EE.SE are fairly good at predicting which question will work better where. On the other hand, a lot of new users and infrequent users are not aware that Arduino.SE exists. They should be enlightened about the existence of Arduino.SE.