Splinto, the developer of one of our favorite calendar apps, Simple Calendar, is offering users a couple of their in-app purchases free of charge. For a limited time, you can get the "Frodo" and "Gob" live tile themes at no cost to you.
It isn't yet clear how long this promotion will last, so the sooner you act, the better. The newly-reduced price was just implemented, so if you don't yet see it reflected, keep checking back.
We have also learned that an update is coming for Simple Calendar that will allow you to choose a tile background color, rather than just being limited to your current phone theme. That update should be rolling out in the coming weeks and we'll keep you posted when that happens.
If you don't have Simple Calendar yet, we recommend you check it out here in the Store. Windows Phone 8 only.