QEMU Advent Calendar is running again this year. Each day from December 1st through 24th a surprise QEMU disk image will be released for your entertainment.
Check out the website on December 1st for the first disk image:
https://www.qemu-advent-calendar.org/2018/
Thomas Huth is organizing QEMU Advent Calendar 2018 with the help of others from the QEMU community. If you want to contribute a disk image, take a look at the call for images email.