When your fruits and veggies are about to go bad freeze them.
Bananas freeze very well, as do berries (and berries are great to eat out of the bag frozen). I freeze bananas and berries individually and then toss all the frozen product into a dated bread bag. The bananas are great in pancakes, bread, muffins, smoothies, and so on.
Bell peppers starting to go bad get diced in the food processor and placed in 1/4 c. portions into ziploc bags. The bags are dated and placed in a bread bag in the freezer. Same with onions. It is so nice to be able to grab a baggie and toss the contents into a recipe without having to do the knife work.
Carrots and celery I cook before freezing.
If you've got a fruit or veggie and you're not sure of freeze-a-bility google and find out.
What other produce do you freeze? Any tips or suggestions?