"Bear ye one anothers burdens." Galatians 6:2
"Being good is commendable, but only when it is combined with doing good is it useful." ~Author Unknown

Activities:

We put together "care bags" with our homeschool group. These were just brown paper lunch sacks. We each brought some items to include in the bags. The kids decorated the bags and then we stuffed them with the items. Now, when we are out and about and come across a person in need (holding a sign, etc) we can give them a "care bag", full of items they can use. Here are some suggestions of things to include in the bags.
peanut butter crackers
shave cream/razor combo
toothbrush
toothpaste
kleenex tissues (travel size)
other toiletries...
small bag of salted peanuts or other kind of nuts (think protein)
pudding
applesauce/fruit
plastic spoon
address/location/telephone of the local Rescue Mission
canned SPAM/Vienna sausage with plastic fork?
fleece scarf (you can often find fabric remnants at Walmart/Fabric stores for really cheap, then just cut them yourself)
gift certificates (like the dollar kind from McDonalds) that they could use for food, but could not redeem for money
YOUR IDEA HERE

Learn about Saint Martin. It just so happens that the time we are doing this, St. Martin's Day is this week, but you could learn about him and what he did to care for and help the poor and sick at any time of the year! Saint Martin ripped his cloak in half, and gave half to a beggar. We'll be doing a lantern walk and then ripping (cutting) our cloaks in half (someone in our homeschooling group made all the kids a cloak) and exchanging them with a friend to imitate what Saint Martin did.
St. Martin's Day website with brief overview.

Help raise money/goods for a good cause. Find an organization and organize/help organize an event to raise money or goods for that organization. We will be participating in an art carnival to benefit the Me Fine Foundation. We'll be donating art supplies (as our "cover charge") and all the kids in our group have been busy creating art for the past few weeks. All the art will be up for sale, the kids and adults will buy the art (for .25 each) and all the proceeds of the sales will go to the foundation. The adults are also donating art to be auctioned off in a silent auction (for larger amounts of money). There will also be craft tables, where for .25 you can make a project to take home. Again, all the money goes to the foundation. The kids will get to have a great time creating art, and buying their friends art, as well as providing both money and art supplies for sick children.

Help care for the environment. Do a park clean-up day at a local park. Just walking the trail and picking up paper/plastic/aluminum trash to be recycled.