I do this all the time, but of course, I can't think of many examples at the moment...
Two things I did recently involve my vacation though. I wanted to just take one bag (trip to Sweden and Finland from the US) and, because I bought cheap flights, my carry-on had to be under 17.5 lbs (no checked bag, 9 days).
I learned a trick a few months before the trip to make your own shampoo and conditioner concentrate, so you could pack it in a smaller container. I had a few bottles of a nice hotel shampoo, in those little hotel-sized bottles. I left one open and let the moisture evaporate for a week or two, then poured more shampoo into the bottle. I did this over several months until I had more than enough concentrated shampoo for my trip. For the conditioner, I did the same, but I put my own conditioner into the hotel bottle (my hair is curly/wavy and somewhat picky).
I get a new pair of work shoes every year. Some years my old ones are falling apart by the time I get new shoes, other times they still have some life in them. I took one pair as my extra shoes, just added some nice insoles. When it was time to come home, they were pretty much used up, so I dropped them in the trash can on my way to the airport (I kept the insoles though). I also bring older socks and underwear that are pretty worn, might have holes in them, when I go on vacation. After wearing them, I finally toss them in the trash so I don't have to wash them or bring them home.