Dnevniki (diaries)
60Words is an exciting new tool that will help you master languages faster (the vocabulary part). You can already register to receive an email when the service is ready (expected time: 2 months or more).
Diamind
(Dia - lat. for "day")
This is a very friendly algorithm that enables you to determine the day of week for any given date in the future. Among similar algorithms this one is the simplest and easiest to use. After some training you'll be able to get the result in seconds without using paper and pen. You cannot say this isn't pretty cool - especially when you don't have a calendar at hand.
I will try to put this in a web-app form soon, but for now it is the Excel template. Download it here and have fun!