I really love this lens... despite there being a small flaw in it I can't do anything about.
This is an example of Nikon's 20mm f/2.8D AF wide angle lens... and something that is rarely out of my camera bag.
The compact ultra-wideangle lens construction with Close-Range Correction (CRC) system offers 94 degree picture coverage with edge-to-edge sharpness.
Do I sound like a salesman? 
While I often use this lens for landscapes and seascapes, it also comes in handy for capturing images like this:
and this



ajnspencer
Pro

I've got a pair of primes, 28mm and 50mm and I love em, amazingly good for the price, they're Canon's cheapest lenses if you don't count kit zooms.

I like to pop one on and go out without any extra zooms, see what I can do with just one view
If I win the lottery one of my first buys will be the ultra-wide completely corrected Canon 14mm L lens, it's amazing that something that short can come wth no distortion.