...juice them and freeze the juice for later use (it's way too cold for lemonade this time of year).
Last weekend, I was strolling around Bar Harbor when I passed a large box of lemons marked "FREE" in the doorway of a gift shop. I crouched down and loaded up my bag until I had about a dozen and began to feel greedy. In retrospect, I should have just lifted the whole box and put it in the back of my car. I use a lot of lemon juice in baking, salad dressing, tahini sauce, and pasta dishes; I'm always running out of lemons.
I juiced these lemons using my trusty wooden reamer (good exercise!), strained out the seeds and pulp, and poured the juice into an ice cube tray (one cube = 2 tablespoons). Now I'm stocked for at least the next month. I can thaw the cubes for cooking, or toss them into hot tea or sparkling water.
I don't often get the chance to live out a folksy metaphor: I can't throw stones from the comfort of my own glass house, and if I called the kettle black it wouldn't acknowledge me. But thanks, life, for the lemons! I've put them to good use.