This interactive heat map shows how common your birthday is. Looks like people make New Year's resolutions to make babies. It also looks like there's some preference to have a baby a few days before Christmas or a couple days after. I'm sure you can see some patterns I missed.
This is a great data vizualization tool. I've been thinking more and more about data viz. I ended up doing some of it for my experiment just so I could see what was going on behind those spreadsheets full of numbers.