Ginger keeps indefinitely in the fridge if you peel (or scrape) it, cut it into "coins" and put in a jar which you then fill with sherry (or not "fill", but you want the ginger to be under the sherry level). Bonus: the leftover sherry is great added to stir-fry-type things.
I use leftover parsley in green sauce: take off the cruddy-looking parts, add lemon juice (maybe one lemon per full batch of parsley), enough olive oil to get the stuff to emulsify (I dunno, start with 1/3 cup and add more if necessary), and salt to taste. grind to bits with a immersion blender. When it's smooth and tastes good, you're done. This is great on anything bean and/or tomato-related, or on grilled meat. If you want to get really fancy, you can toss in an anchovy or two.
We had homemade pizza for dinner: DS15 wants to take pizza slices for lunches this week, so WTF, why not: we made 5 (three small ones for dinner, and two more for his lunches) with mushrooms, marinated peppers, tiny pieces of salami, and I used up a couple of TB of leftover goat cheese on one of them.