Just wanted to add a quick post about natural fertility control. I've been using Persona successfully for a couple of years now - it's absolutely great. I'd only use it in a long-term relationship though, you wouldn't want to get HIV or a venereal disease. Even if you're only having casual sex, it's good to know when your fertile times are, because condoms do burst, and a friend of mine recently got an unwanted pregnancy by using the honey cap on her fertile days.

Here's the link

http://www.persona.info

I recommend taking a natural family planning class along with using that, so you can identify fertile mucus. That test will tell you when you ovulate, but it's the fertile mucus that can preserve viable sperm up until ovulation.