I'm sure everyone knows about the pink ribbon Tifa wears on her arm. I always thought it had something to do with Aeris. But then I noticed something interesting...
Cid wears one, too!
Thus sparked my search for what the red ribbon means. I've found that Yuffie (you gotta squint, its on her right arm) and perhaps RedXIII (you can makeout a little pink on his right...paw/arm) also wear one. You can't tell if Barett or Vincent have one (those sillies) and for a while I thought the same for Cloud, until my friend told me that in the 4th trailer he IS in fact wearing one (I haven't seen it yet).
The ribbon could either mean two (or more) things: A) It has something to do with remembering Aeris or B) It's something they perhaps donned after splitting up, for sentimental value? To remember Avalanche? Or their comradery? Maybe it's a new fashion trend? It is like the Livestrong bracelet?! Why doesn't Vincent have a new little outfit? Does he wash it? Does he have others just like it in his closet? Does he have a closet? Maybe he sleeps in it? Is he smelly?
Okay I'm done.