Textile craft stuff just is so versatile, and here's two examples of it. First of all, a really nice article about knitting spies and knitted secret messages - though I'm rather convinced it's not a dropped stitch that actually happened, but something like a yarnover.

Knitting codes is definitely fun - the most patient husband of them all knit yoga socks that morse code spell out "Yoga socks", and he had a lot of fun with that. I've yet to do something similarly geeky, but it is on my list. (Though not very far up the list, I'll admit.)

The second link is not knitting, but crocheting: the clinic in Hannover is giving hand-crafted cuddly snails to children getting cochlea implants (German site). These children are born deaf, and they are getting the implant operation at a very young age - usually still a little less than a year old - which is of course quite exciting and frightening for them and their parents. So the staff of the clinic in Hannover has started a project back in 2015 where each of the about 100 children getting the implant each year gets a hand-crocheted snail to cuddle. It's intended not only as an emotional uplifter for the children, but also as a token of appreciation for this very big step in their lives.

In case you have itchy fingers now, the (German) pdf instructions on how to crochet the snails are linked from their site. And if you love the idea of the snails getting handed to children - all snails are crocheted by volunteers, and the clinic is always looking for snail donations, which are much appreciated.