I wish I could take credit for this idea, but I found it in some publication in some parish's pamphlet rack about a year ago. It's such a wonderful idea on so many levels, that I just had to share it with you all.
Instead of donating the regular type of items to your local food shelf, consider assembling "birthday bags" for kids of different ages. These can be as simple or elaborate as you'd like and provide the makings for a birthday celebration.
On the most basic level, a bag should contain a cake mix, canned frosting, and some cake decorations. You could also add festive paper plates and napkins, a drink mix, balloons, noise-makers and party hats. An even more elaborate bag could include a simple party game (check your local dollar store), some kind of craft project, and prizes for party-goers.
I think this would be a fun project for any kind of church service group or even the participants of the next birthday party you host for your children.