Ok, not really the trash, but the recycling. Since my parents and Hubby's parents come and stay with us periodically, and we have very helpful friends, all who try to clean up after themselves, I was pretty often finding trash and recycling all mixed in together.
I took some gold vinyl letters (the kind you use on a mailbox) leftover from a project from our wedding (being a crazy pack-rat pays off!) and labeled the recycling bins. And VOILA! No more mix ups!