name calling at its best

I send a lot of emails to a variety of groups in my company. A LOT. My standard greeting is something along the lines of, "Hi, all ..." or "Good morning, all ..."

But that's boring. I'd like to come up with a variety of interesting and fun things to call groups of people. I've successfully deployed "dynamos" (thanks, eestiplika!), and I want more ideas. What are some other fun, playful things that I could call people in a professional setting?