CE, pretty much everything in the last section is non-Magic, really (except for the Trading Post). Gaming, Battle, Suggestions, and Testing (I don't count the last two as dealing WITH Magic, they're more board specific). I don't know if the number of posts outnumbers the Magic-related forums, but I would guess it's more closer to 50/50.
Duel: Not sure what you're getting at
. THIS thread is Magic and community... but these types of threads don't appear all that often. For a while the bulk of threads was discussing 7th/Planeshift cards...