Need to bring a dish to share to a get-together and don't want to spend a lot and only want to use what you have in your home? Why not bring Soda Cake?
I recently found out that you can bake a cake with literally just the box of mix (which is about $0.50 if you use a coupon) and a can/12oz of soda.
Just mix the 12 oz of soda with your cake mix and pop in the oven according to the directions. Some people say to bake for an additional 5 minutes to make sure all the liquid is absorbed into the cake, but it doesn't really matter.
I have one baking in the over now that I'm taking to a Wii Bowling league get together. Not bad for having to feed several people for less than $1.