Before DH and I started using NFP (Natural Family Planning) as contraception we used the withdrawal method. Neither of us were keen on the idea of me taking synthetic hormones every day and sometimes condoms can be a pain so.... anyways, it worked for us! I think the problem is alot of men pull out literally the split second before they ejaculate- and this can result in some spermies sneaking through. I think it is much wiser for the male to pull out at least a few seconds before- IYKWIM. Having said that - you still hear of those rare few who do fall pregnant with this method so its certainly not foolproof (of course neither is the pill or condoms).
In my experience, NFP is the easiest and most effective way to avoid (or acheive) a pregnancy. You just have sex when you are infertile (and the male can enjoy the indulgence of ejaculating 'within') and avoid intercourse when you are fertile (of course sexual pleasure can be acheived in other ways during this period).
Its a very empowering method, especially for the woman- as you feel completely in tune with your body's natural rythym and ultimately you control when it can and cannot happen.
The only challenging part IMO is that the woman feels most like intercourse when she is fertile (natures way)- and so resisting the temptation to go 'all the way' in this short period can be tough sometimes. Also- women with irregular cycles have to be more vigilant at monitoring their cycles and symptoms of fertility and infertility- although this gets easier with practise.
The best thing is, it does not affect your fertility in the long run - like the hormonal contraceptives do.
OK- I have just rambled on here..... sorry!