Double Sided Knitting - http://www.knittingstory.eu/double-sided-knitting/
This site has tons of helpful video tutorials to teach you how to knit.
A double knitted baby blanket for counting stars: Octave or Octavie by imawale imawale [Una copertina da neonato lavorata con la tecnica del double knitting per contare le stelle: Octave or Octavie di imawale imawale]
double knit cast on. This could be a neat way of casting on without seeing the cast on stitches.
Ravelry: #25 Double Knit Winged Triangle Shawl pattern by Tania Richter. Vogue Knitting Fall 2015
Double Knitting - How to Knit Two Layers of Reversible Fabric at the Same Time
Star Wars Double Knit Scarf - Most impressive. Get the pattern & charts! #starwars #knit #knitting
Baby Love Double Knit Baby's Heart Blanket by QueenOfTheTeaCosies
Star Wars double-knit scarf (and there's a pattern at the link)
Simple Double Knit Tutorial I think this could be very useful for the soles on slippers..