I have clicky fingers too! I can make my nuckles click, as well as my toes! I have really double jointed fingers than can bend all the way back, and i also have hitchhikers thumb, where my thumbs can bend backwards more than 100 degrees!
I was told by my parents friend (I think shes a physiopherapist, or something along those lines that involve bending people and fixing pains and injuries!?), and she said that it's nothing to worry about, and wont lead to arthritus or anything, and the clicking noise is just little pockets of gas (which is supposed to be there) popping, and making a noise!
It shouldn't cause arthritus, but if you keep clicking your fingers a lot in odd ways, it can lead to RSI (repetitive strain injury), which can hurt!
Jacob.