It seems to be a bit of a waste just to toss all the leftover pulp after juicing, so here is some suggestions to make better use of the pulp:
Orange & Lemon (citrus fruits) pulp:
Use it in an Orange or Lemon Cake
Pulp from water melon, honey dew, pineapple, berries etc :
Mix it in with a Fruit Salad
Use the pulp in a Carrot Cake
Mix it in with mince meat and make meat balls, meat loaf or other meat dish
Tomatoes, greens, herbs:
Add it to a tomato pasta sauce
Use it in an Apple pie or Apple sauce
You can also add pulp to Breads, Pancakes, Muffins, Soups and Dips.
If you don't want to use it in cooking you can compost it.
I'm sure you can think of many more ideas, but these were just a few.