The "Natural" Family Planning Technique

WARNING: Some of the information contained in this post may or may not gross you out. So if you're a guy (specifically my husband) or if you find human sexual anatomy gross in any way, you may not want to read anymore. Consider yourself warned.

I've heard this called many athings. I've heard "not trying, not preventing," which in my book, IS trying--Which I may have been accused of in this post. But I beg to differ... I think people who may say "I'm not prevention at all, but leaving it up to the Lord" in turn will probably wind up pregnant, while those of us who are preventing still but say "If it still happens than maybe it was the Lord's will" is kind of a logical statement. I think if you're using SOME form of protection/prevention then you're not expecting to get pregnant. However, I do understand that my methods now may not be as effective, I'm still doing my best to stay un-pregnant.

One way I'm doing that is researching the Natural Family Planning or "NFP" method and/or the Fertility Awareness or "FAM" method. For now, I've just been mapping it all using the rhythmic method. I've been charting my days and what not and have been trying to avoid--(Ya know)--on certain days. I even downloaded a free iPhone application from Fertility Friend to keep track. It's REALLY helpful! Their website is nice too.
I've also heard of the ovulation/billings method, which seems a little more complex and takes more effort. You watch more for signs from your body, take your temperature a lot and check all sorts of nasty anatomy stuff. I bought a basal thermometer that I'm hoping to try to use, and map out my minor degree changes from day to day. If anything this should be a fun experiment right?

Here's my plan: Track as much as I can so I know what days to AVOID, and in turn, when it's baby makin' time, hopefully I'll have it down. But for now, I'll try to count and figure out the days, and keep using the magic gel (every time regardless) and hope I don't wind up pregnant for at least a few more months. I hear these methods work pretty well when used correctly.
I'm actually interested in finding more books on this topic. I know a lot of my friends tried this because they don't like hormones. Most of them are pregnant now, but I think it's because they weren't trying hard enough. At least that's what I'm telling myself so I have the confidence to make it though.

I hear this way of tracking is great for when you're TTC too because you'll know your cycle very well. Part of me doesn't get that though... Can't you just do it every day? That's one way to try to make a baby. At least that covers all of your bases! That's my plan at least.

I dunno, what do you think? Have you tried this method before? It work for you? Have any books or sites to recommend?