I thought this was a great question, so I have put together some of my favorites for you. I was pleasantly surprised to find installation images of all but one color.
Benjamin Moore's River Reflections
Benjamin Moore's Titanium OC-49
Sherwin Williams' Analytical Gray (very warm)
Sherwin Williams' Tinsmith
Sherwin Williams' Thunder Gray
Sherwin Williams' Pussywillow
Sherwin Williams' Collonade Gray
Farrow & Ball's Charleston Gray
Farrow & Ball's Pavilion Gray
Hopefully, this little list of mine is helpful for those of you who are in the market for a good gray as well.