Volunteering in India

I would love to volunteer in India in some capacity working with children and young people as that is my passion, I am not fussy where or even the duration as I can be flexible, I get to India (Chennai) on the 8th September. However all the sites I can find require me to pay to volunteer and unfortunately thats something I just cant afford to do... Does anyone have contact with any agencies that are free to volunteer through or know of any worthwile causes I should try and seek out directly?

I know of 2 useful groups near Chennai in Pondicherry. Check out India Volunteercare or Primetrust They charge a small orientation fee (it's not much - about 100 euros) but essentially they give training and take good care of you. Definitely worthwhile. I did a stint with the first.