Women are sometimes loath to admit that it's "that time of the month," meaning guys can easily be blindsided by those surprise hormonal tantrums that seem very loosely based in reality.

But now there's a new site that can help you. Denver entrepreneur Jordan Eisenberg has recently launched PMSBuddy.com to help you track the cycles of the lady in your life. All you've got to do is enter the date of your partner's last cycle, and the site will automatically send you e-mails to warn you before her future cycles. The warning can come from one to five days in advance.

Eisenberg's site has a pretty smart business model -- he's set up corporate partnerships with 1-800-Flowers and Godiva chocolates, and gives recommendations about how to soothe frayed nerves.

The site has already attracted thousands of visitors from around the world, but be careful -- it's doubtful your lady will react well if she finds out you've been charting her hormonal life, especially if she finds out during those fateful five to seven days.