All shades of white on walls will always be a classic and popular choice but I have to say it's really nice to see these deep greys making an appearance. I have a client at present with grey walls and it's amazing how the colour changes during the day - some times with a green tone, other times slightly brown.
The top two images are from the cool Ilse Crawford. These rooms are from the Whitechapel Depot in Notting Hill. The black and white details look great against the grey. The crisp white walls and ceiling help balance the grey and keeps it very modern.
The last three images are from Nate Berkus. The first one, overall very harmonious. The second one - I especially like how the leather chair just glows warmly against the dark walls. And the last one - the layering of greys on greys with walls, table and bench seat in various shades and letting the white lamp and neutral sofa stand out.