A penny saved is a penny...donated:

What do you do with all the change you get? I put mine in a Mason jar until it is full. I used to take it to the grocery store to one of their cash machines, but the machine takes a hefty chunk as a percentage of the transaction... So now I save it for charity drives. It is money I've gotten along without, so donating it is painless. Grocery stores usually have a collection going on;  McDonalds collects coins for their charity, Keep your eyes open. When possible, have your little ones put the coins in the collection pots. Not only will it get them excited about helping others, but this is a great way to donate without making a dent in your budget.

Here are some other very low cost ways of helping others:
$10 to malarianomore.org will buy one mosquito net to protect one child from malaria for 5 years.
$20 to charitywater.org can give one person drinking water for 20 years!
$35 to unicefusa.org buys a bike to get a health worker to remote areas.
$35 to scaw.org provides bedding, clothing, school supplies and other needed items for a needy child.
$50 to yellowribbonfund.com provides a rental car for a wounded soldier's familly while he or she is at a military hospital.

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Sit down with your family and decide which charity you'd like to help and have the whole family contribute something. Get a jar and have each person take money out of their allowance, or donate any coins they find around the house. For very small children, you can "find" a quarter and let them donate it to the jar. (of course you're not going to send the actual coins to the charities, you'll write a check or make an online donation - the point is, the whole family gets to share in the joy of giving).