Using a lemon for its juice only? Don't waste the zest! Zest the lemon (either in little pieces with a zester or peel it with a veggie peeler) and place the pieces in a baggie in the freezer. Whenever you need lemon zest, bam! It's in the freezer for you! Then take the left over rinds and rough cut them. Place these lemon chunks in your garbage disposal and give it a whirl. They will freshen your garbage disposal in a flash!
What if you have lemons that need to be used or you just needed the zest of the lemon... Well you can save the juice in the freezer too! Just juice your lemons into ice cube trays and voila, instant lemon juice when you need it!