Kids of all ages can sort through their toys and select a few to donate. An older child and his friends might repair, clean, and wrap items before delivering them.
Volunteering is a great way for kids to see first-hand how their good deeds can affect others. Older children could parlay a particular talent into a charitable activity by playing the piano or singing holiday carols with a group of friends at a nearby senior center. Both parents and children could volunteer to hand out bags of food at a food bank or offer to walk dogs at a local animal shelter.
Pick causes to support as a family. Label a jar for each charity, and drop in any loose change daily. Then, send in the proceeds.
Encourage kids to raise money to give; let them come up with a plan and execute it. For instance, they may wrap presents for neighbors for $1 per gift and then drop off what they earn to an organization they've researched.