This is one - it has pictures, which you might not want to look at but I've got to admit I did not know loads of this stuff such as the fact that it sort of hangs in your vagina and moves lower, higher etc!
http://www.sisterzeus.com/cervob.htm - take some of this with a pinch of salt though, such as "All you need is a plastic speculum, a mirror and a flashlight" - you're not going on an adventure and where would you get a 'speculum'
I check a few times a month such around OV to see if it is high and soft.