When we were kids, we loved advent calendars, those big cards with little pop-out windows offering a surprise for each day before Christmas. We were wishing we had one of those, and then we stumbled on something better: The Big Picture’s Hubble Space Telescope Digital Advent Calendar. Each day reveals a new awe-inspiring photo from Hubble, from now until Christmas (There’s even a temporary RSS feed.) And like a regular advent calendar, the coming windows are blank – leaving that pleasant feeling of anticipation.