Trying really hard to have a baby? Trying really hard not to?

The nice, slightly intrusive folks at BabyCenter.com can aid your cause with the "Booty Caller," a free text-messaging service that tracks your menstrual cycle and lets you know when you're ovulating. Enter the date of your last period and your cell phone number, and you'll receive alerts letting you know when you're extra fertile, along with helpful, kind-of-icky tips. (Did you know that lube can impede conception? No? Now you do!)

Booty Caller subscriber Nancy Evers told the Seattle Times that both she and her husband use the service. After they get the texts, they message each other and "get all flirty" until they can be together. (The reporter from the Times lamented, "It would be nice if they remembered to have sex on their own.")

Clearly, the tool was designed for women who are trying to conceive, but we think it would be extra helpful for those of us who aren't. If you're trying to make babies, your text will be your signal to run home to your significant other for wild, unprotected sex. If you're not, it's a signal to lock the liquor cabinet and delete your ex's telephone number.

Perhaps in the future, the service can take more direct sex-inhibiting measures, like automatically texting your guy "We need to talk" and "I feel fat" before you get home.

Use caution, however: The Booty Caller doesn't account for changes in your cycle, and every woman's biology is different. So unless your ovaries run like a Swiss cuckoo clock, use more conventional scientific methods.