• The Baby Chain also lets you donate items and find used items in your own area.
• If you haven't used it yet, Freecycle is a great way to just give stuff away. It's so quick and easy and you'll be free from all that clutter.
• Room to Grow will take your clothes and gear in New York and Boston for children living in poverty.
• Newborns in Need will give your stuff to families in need.
Find the links and a few more ideas over at Cookie.
Look for local parents groups and classifieds in your area as well. We have a few of those here in Brooklyn and find them quite useful. If you can, give your stuff away to someone who will appreciate it.