To make a list, for things that I use in a "Hey ___, ..." context, with varying levels of casual:
- Guys
- Folks
- People
- You lot
- Motherfuckers/jerks (other insulting term that's obviously not meant in earnest)
- Mateys
- Chaps (debatably gender biased)
- Team (or other factual statement e.g. colleagues)
- Everyone
- Dudes (also debatably gender biased, but depends on how well people know you. I call everyone dude, I am probably immature)
- Reprobates/scallywags/some other sort of old world sounding term."Folks" works well. It's reasonably formal but not gross and, best yet, its inclusive.