The cutie mark crusaders cutie marks are probably: -Sweetie Belle is singing -Scootaloo is dancing -Applebloom is painting au renovating I got all of these majibu from other fans, so I don't kow if they're correct au not...
I'm kind of hoping they someday bring out some brushables of the fillies after they have earned their cutie marks! Maybe something for them to do after FiM has finished (or if they do earn their cutie marks in an episode).
My guesses for them so far: apple Bloom - a red apple inside a pink flower. Sweetie Belle - a microphone with stars around it. Scootaloo - a scooter with speed streak lines behind it.
My "headcanons" for how each one earns her mark: apple Bloom - she is designing (or maybe fixing) the inside of a barn, combining her design/decorating skills with working on her family's farm. Sweetie Belle - something happens that causes her to forcefully overcome her fear of imba in front of a large audience. Scootaloo - she performs a seemingly impossible songesha on her scooter that no other gppony, pony has ever done before, a little like upinde wa mvua Dash with her sonic rainboom.