A modern canopy bed by Jean Louis Denoit
To many people, the thought of a canopy bed would give them the creeps.  Not to blame them if the first image that easily slips into our minds is a frightening postcard from The Jacobean period style.   A heavily carved gilded bed with a heavy cornice, swags hanging from the canopy and so much fabric enclosing you is for sure a recipe for rhinitis.  Today's canopy beds couldn't be farther from that and you don't need a four poster bed to create one.  Anyone with a regular bed can build one with curtain rods and fabric securely hanging from the ceiling.  Check out YouTube for some cool tutorials or head over to Lonny Magazine where Michelle Adams documents how she made hers.   
Whichever way you decide to make one, a canopy over the bed is one of the most romantic ways to decorate your bedroom. 
Via Southern Accents
An upholstered crown canopy bed via Architectural Digest.
By hanging a big piece of fabric from two curtain rods is a very easy way to create the canopy feel.
Dara Caponigro bedroom
I love to see them hanging direct from the ceiling.  It makes the rooms look bigger.
By Jamie Creel via Elle Decor
This is way more elaborate and professionally done by Phoebe Howard. 
Design by Katie Ridder via Elle Decor.  A perfect girls canopy.
In the picture above the canopy seems to be hanging over the bed from curtain rods and chain.  Designed by Mark D. Sikes