If you have an iPhone or iPad, I guarantee that it will do things that you don't know about. I found this Buzzfeed list by way of another quilter's facebook post (thanks to Frieda!) and I learned a few things. The real trick will be remembering them.
It's good to know how to save a google map so that you can access it even if your device can't connect to the internet (#3) but the trick for deleting a wrong number in the calculator is something I'm more likely to find useful:
I didn't know that you can add a folder to the icon bar or the domain name trick in #17. It's nice to learn new things!