The Mighty Bottle/Package Cap
Problem A — you have a bag full of empty plastic bottles that you're too lazy to recycle. Problem B — you have tons of package bags that should be closed, but you don't have any bag clips on hand.
The solution? This hack! Carefully cut the top of the bottle. Once you have that, uncap the bottle piece and thread the opening of your bag through. Then, just seal your bag with the bottle cap, and you're done!