I try not to bring anything non-essential, but, well, you know.....
I have a flat magnifying glass that I got at an IRS seminar. Takes zero space, but it does the trick. Also, I take a flimsy plastic cutting board. It's a divider in my suitcase. It's a cutting board for cheese. It's a plate for pastries or sandwiches in the room. Sporks are a must for on-the-go meals, and mine has a knife edge. A very basic first aid kit.
But you can always go shopping. Lots of cities have Sephora stores -- go in and look around, buy a face mask, which is a terrific way to rejuvenate on the road. Same thing for L'Occitane. These may be exotic brands to us, but in Europe, they are run-of-the-mill. In fact, some variety stores sell L'Occitane, so if you run out of that essential foot cream (and it is essential, trust me), you can usually find an outlet for more. Really. Try the foot cream. It seems to cure blisters overnight and just applying it at night is so soothing.
Also, I don't bring home things that I can buy here. Luxardo cherries are available at Williams Sonoma and also World Market -- probably other places, too. I was going to buy pasta in Italy, but Williams Sonoma sold the exact same packages here, so why drag it back? The potato chips in Spain? Unbelievably good, and available at La Tienda and Amazon! I once (and only once!) spent a lot of money to ship wine back from Italy from the winery that we visited -- only to find it here at home at Binny's! (I was very happy to find it at Binny's!)
Plus one of my favorite things to do when traveling is to explore grocery, drug, housewares and hardware stores. Fascinating. Who among us hasn't flipped at City Pharma in Paris? Great gifts, too!
I'm beginning to collect address tiles from the countries I visit, and hardware stores are a good source. They are flat, easy to pack. (Think the blue enamel tiles in France and ceramic ones from Spain.)
I travel with a carry-on that I usually check because of the fluids, but this year, I'm ditching the non-essential fluids and buying them in Europe.