If you're trying to conceive or trying to avoid it, I'd recommend taking a look at this article, which I read on natural-fertility-info.com. It discusses several different ways that you can monitor your fertility, including ovulation predictor kits, basal body temperature charting and one method I'd never heard of before.
Did you know that your saliva can help you predict when you're most likely to get pregnant? Oh yes. And it gets better. To see what your spit is telling you, you get a hand-held microscope...and lick it. The pattern you see will change as you get closer to ovulation.
I am not making this up. But I do think it's kinda funny.