I'd check with your local homeless shelters and food banks to see if they have suggestions. One thing we can do here is to make sandwiches (at home or at school or with church groups etc) and then deliver them to a local shelter - the shelter either uses them right away or freezes them. Something like that you could have your dd do at home and you could make it a monthly or weekly or whatever commitment for yourselves.
If you have a shelter that helps families with young children, that might be a good place to take your child to deliver things like either one-time toy donations or book donations or for instance, we have a local shelter for single moms that really appreciates donations of fresh fruit.
It's also the time of year during holiday season in the US that you can usually find families who can be "adopted" for the holidays - how much you'd help or give to the family is going to depend on what's asked for and the organization that's organizing the program, but I found when my children were small that choosing a child's name off of a wish list where they could pick out a gift for the child for Christmas was an easy and meaningful way for them to participate in helping others.
I think it might be too late for it this year, but our kids also have loved the Samaritan's Purse box project where you fill up a box for either a boy or girl of a certain age and it's sent to a child in a different country. You can google Samaritan's Purse to find out more about it - I think the name of the program is "Operation Christmas".
One of our local homeless shelters has a similar program where families fill up a shoebox with socks, toothpaste/toothbrush/warm gloves, hat, kleenex - things needed by the people the shelter helps, and each box goes to one person - when my kids did projects like that they liked it because even though they didn't know who the box would go to they felt a connection because they knew they were preparing it for a specific person, not just collecting things to go into a larger collection of things to then be distributed.
At the beginning of each school year, there is a local group here who holds a big drive for school supplies and winter coats for kids who need them. It's too late for this year, but it's something that children can identify with. I think I've heard of organizations in other areas that keep supply "stores" for things like this year-round.
Totally different twist, but my kids like running in running events organized to benefit charities, and they understand that the money raised by paying an entry fee and/or raising money based on your own participation goes to helping others.
One other thing my kids have done - they've helped distribute food at our food bank.
Another thing to think about for your dd - does she go to Sunday School or is she part of any other organized group like preschool or a sport? If she is, you or another adult could help her make an idea of hers grow into something special by helping her ask her group to participate - for instance, collecting books or outgrown toys or clothes for a kids' shelter. Seeing how coming together on a project like this can make a simple donation grow into something "big" Is really cool - and it doesn't have to be a huge donation, just the act of sharing in the giving is neat, and it shows our kids they can be a seed for meaningful acts

polarbear