Good Blues...

True blue - someone loyal and faithful
Out of the blue - unexpected (could be positive or negative)
Blue ribbon - first rate, top prize
Blueblood - person of noble birth, royalty
Bluestocking - well-read or scholarly woman
Bluebook - register of socially prominent people
The Blues (capitalized) - popular style of music sometimes characterized by melancholy melodies and words
Baby blues - Blue eyes