This started off as a goofy one-off because I thought day of year
was missing from UNIX date.
Spoiler: it's %j. So, I wrote a ten line Objective-C program to emit Day ##.
I realized having a few pieces of data on my watch like, "Today is the 2nd Thursday which means I need to move my car" would be useful. Now it's an app that I can't ship because everything is hard-coded.
I might change that someday.