This is our latest free application for women – period and fertility calendar. Here is what it does:

• Figure out your most fertile dates
• Find out expected due date
• See the approximate date of your next period
• Store history of your periods so you never forget them and be prepared on time

Some technical background (because many developers read this blog):

It’s HTML 5 Ajax app with localStorage support. I’m not yet ready with the pluggable open source version, but you can see the front-end javacsript with View Source.