You can be feeling blue; be singing the blues; maybe you're a blue sky thinker; been talking until you're blue in the face; be a blue collar worker; have blue blood; be blue from the cold; be wearing something borrowed, something blue; or you're true blue.
Blue is the sky, and the sea. It can also represent hope - probably from a blue sky as well. Interestingly, it has also come to represent depression and sadness. It is sometimes also seen as a spiritual colour. It is often also associated with cold, and ice or snow.
Common connotations with blue are sky, sea, berry, music, jazz, ice, cold, snow, sad, depressed, ink, common/regular, boy, jeans, water, spirit, peace, harmony, serenity, calm, stillness, bird, bell, and sometimes night (ala Vincent van Gogh's Starry Night, found below).
Lighter shades will often bring to mind generally lighter connotations, and darker shades the opposite, as was mentioned before.
Blue used to be my favourite colour. It brings to mind dreams of flying (daydreams; I don't seem to get night dreams of flying) through the blue skies, and days at the beach looking out at the blue ocean. It's also possibly the colour my eyes are. I can never quite tell. They're either blue, or the next colour. I'd prefer the next colour. It also brings to mind peace, calm, and tranquility; it sort of hangs around for a while, unlike a hotter colour that just flashes at you.
The song for today is Electric Blue, by Icehouse.
P.S. Sorry this has taken so long to get up. Been busy/distracted. Rest coming up shortly, fingers crossed.