Over on Facebook someone shared with me this video about the use of yarncrafts in mathematics: 
https://www.facebook.com/mentalflossmagazine/videos/10154510337972365/
Here's the accompanying article:
http://mentalfloss.com/article/86016/6-math-concepts-explained-knitting-and-crochet
I've been collecting links about this subject for a while so I offered to do a linkspam.
Particularly rich sites to investigate:
https://www.facebook.com/mentalflossmagazine/videos/10154510337972365/
Here's the accompanying article:
http://mentalfloss.com/article/86016/6-math-concepts-explained-knitting-and-crochet
I've been collecting links about this subject for a while so I offered to do a linkspam.
Particularly rich sites to investigate:
- Dr. Sarah-Marie Belcastro's mathematical knitting page.
 - http://www.toroidalsnark.net/mathknit.html
 - WoollyThoughts.com, the yarncraft home of mathematicians Pat Ashforth & Steve Plummer.
 - http://www.woollythoughts.com/
- They also have a Ravelry group.
 - http://www.ravelry.com/groups/woolly-thoughts
  - They also have a Ravelry group.
 
- The original paper about crocheting and mounting the Lorenz manifold.
 - http://research-information.bristol.ac.uk/files/2988096/2004r03.pdf
- Crochet your own Lorenz manifold
 - http://www.ravelry.com/patterns/library/lorenz-manifold
  - Crochet your own Lorenz manifold
 - An interview with the people who designed and crocheted a hyperbolic plane.
 - http://www.cabinetmagazine.org/issues/16/crocheting.php
 - Mary Pat Campbell's fractal crochet 
 - http://www.ravelry.com/patterns/library/crochet-sierpinski-fractal-triangle
- http://www.marypat.org/stuff/nylife/020325.html
 - Gallery of sierpinski crochet
 - http://www.crochetgeek.net/crochet/sierpinski/gallery/index.html
  - http://www.marypat.org/stuff/nylife/020325.html
 - Random stripe generator
 - http://www.biscuitsandjam.com/stripe_maker.php
 - Tessellated fish
 - http://www.ravelry.com/patterns/library/a-recipe-for-fish
 - A recipe for knitting a Klein bottle (which can be worn as a hat)
 - http://www.toroidalsnark.net/mkkb.html#kbinst
 - The Crochet Coral Reef, a project of the Institute for Figuring
 - (this isn't strictly mathematical, but a lot of the creatures depicted grow in ways that can be depicted using hyperbolic plane crochet)
- http://crochetcoralreef.org/coral-reef-gallery.php
 - You can participate in this project. Some example patterns here:
 - http://guides.uflib.ufl.edu/crochetreef/crochetcoralreef/patterns
  - http://crochetcoralreef.org/coral-reef-gallery.php
 - Cable knitting using random numbers
 - http://web.archive.org/web/20130707042959/http://www.fuzzygalore.biz/articles/probability.shtml
 - Knitting using cellular automata
 - http://www.knitting-and.com/knitting/tips/automaton.htm
- Cellular Automaton pattern generator (uses Flash)
 - http://www.unikatissima.de/e/?page_id=2148
 - Cellular automaton pattern examples
 - http://mathworld.wolfram.com/ElementaryCellularAutomaton.html
  - Cellular Automaton pattern generator (uses Flash)