A while back I was working with MS Excel and wanted a pop up calendar. After searching online I had little luck so I decided to create my own. The initial calendar used combo boxes for the month and year selections, I later added a small user form for the months and for now a spin button for the years.
Included with the calendar files is a calendar icon which can be used as a button to activate the calendar. With some small VBA code the date returned can be passed into a cell or variable as required.