i use http://www.fertilityfriend.com/ you can use their free charting. which is you can put in all kinds of data about yourself and it is very user friendly, or if you are looking for more detail, you can subscribe to ther VIP membership. it doesn't cost much. you get a free 14 day free trial of the VIP and then if you let it expire, they will offer you a discounted rate if you decide you like it better than the regular free membership. if you are just tracking your period and cycles for birth control reasons, than the free membership would work, but if you are trying to get pregnant, i would go for the VIP because it will predict when you ovulate, and tell you when you are triphastic and possibly pregnant. that is if you do temps with it though. anyhoo, i am babling, but i highly recomend fertilityfriend.
i also use fertility friend - the free membership provides plenty for me personally, but the paid membership allows access to the forums and isn't very expensive. i find it's extremely easy to enter your temps and other fertility signs and a feature i really like is you can look at other people's charts that are similar to yours, which sometimes helps me when it seems like my temps are all over the place.
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"to be nobody but yourself in a world which is doing its night and day to make you everybody else, means to fight the hardest battle which any human being can fight, and never stop trying." - ee cummings