I wish I would've had this YEARS AGO! I present to you PMSBuddy.com.
This ingenius little website makes sure you don't get blindesided by the PMS from the women in your life ever again. Basically, you sign up, and enter up to five women: friend, mom, girlfriend, roommate, wife, landlord, grocery store checker, whomever. The site then gives YOU forecasts and updates on their cycles and when PMS is just around the corner! The only problem I find here is that you have to know the date of their last cycle, which, depending on who it is, could be difficult/disgusting to obtain. Click pic for more.