There is two things that you can do.....On Yahoo in their GROUPS there is a group called FREECYCLE. I live in Wellington and there is a Wellington Freecycle, I believe there is one closer to you. Once you "join" totally free you "offer" your baby clothing and people will write back to you and tell you they want/need it and you make arrangements for them to pick them up from you.....there are TONS of people who really need the clothing you will have it gone by the end of the day!!!
Another option if it is infant clothes is donating it to your local hospital maternity ward. I did that with my son's infant stuff because when I was giving birth I was chatting with the nurses and they told me women go in having babies everyday and have NOTHING at home for their newborns............
God Bless You!