UX trip: Calendar for birthday
I encountered this annoyance registering my child for a class. First, the form asked for birthday and age, and both were required fields. I was tempted to be inconsistent. The real annoyance was the birthday field. It used a pop-up calendar widget, and did not allow me to type in the field. It started with today's date. To select my child's birthday, I had to navigate back through multiple years of months using arrows, which didn't stay in the same place on the screen because different months have different numbers of weeks (rows), so the widget got taller and shorter. If I missed a button, the widget would go away without changing the date. It would be so much easier to just type the date. Even with a required MM/DD/YYYY format, I'd still be happier.