Irony Games at irony.com has a tool that lets you make your own calenders by creating the months, number of days in each month, phases of the moon, etc. I don't know if that might help.
I highly recommend the old 2nd Edition ADnD World Builder's Guide Book if you can find it anywhere, maybe a used book store would carry it. It has everything, and you can even roll up a random world, the random descriptors arent extremely detailed so you can fill in specific aspects, or you can just keep rolling to get all the details. Very fun stuff.
--RB Gnome