My colleagues and I have noticed something when re-watching Reichenbach Fall for clues...all of the IOUs posted around the episode were red... Lets list:
1. RED apple with IOU carved.
2. RED spray paint saying IOU on windows.
3. RED graffiti on Baker Street saying IOU...
So, what does it mean??? Here are some of my theories...
1. Has some very important meaning that I don't understand.
2. It's a RED herring.
3. Nothing at all, just a coincidence.
4. BBC just chose a simple colour.
5. Moriarty is saying "Hey, Sherlock! It's red! BLOOD! Get it? You're gonna' DIIIIIIIIIEEEEEEE!" because that's the kind of person he is.

INTERESTING...........hmmm? I'd like to hear whatever anybody else thinks about it.