Secret Gmail Keyboard Shortcut[s]?

For those of you who played video games ad nauseum as children (or still do as adults), I imagine this post will have a familiar ring to you.  For example, if you played Metroid, I'm certain you relished the treasure trove of hidden secrets and power ups.  Well, from my view, it looks like I may have found one today.  Behold:

Extra recipient field goodness

That's right kids, unless I am out of your mind, the CA has found a secret Gmail keyboard shortcut: b.  What does this mysterious short cut actually do? you ask.

It opens a new draft email with the cc: and bcc: fields already expanded.  I accept cash, credit card, check, PayPal, or wampum.

I think what I actually feel most mystified about is that upon pressing shift + / (also known as "?"), I fail to find any shortcut listed.  Yet, I guarantee you will see a similar result if you press "b," while outside any text box in Gmail.

You may now applaud.  Thank you.

UPDATE:  It's been brought to my attention that there is actually another variant of the undocumented compose email function: d.  D does essentially the same thing as c or b, except for that d opens only the to: and cc: fields.  Thanks for this additional shortcut, Alex!