My lovely DIY shelf in my guest room using 4 crates stacked together! Simple edge-paint project that ties the colors of the room together immediately. All my guests compliment it all the time. It is very sturdy and holds heavy books to sweaters.
A few wooden lines attached to a plant holder, in random fashion, is the easiest way to beautify the white walls of a small balcony. Again, different plants in pots of various shapes and sizes lends an effortless quirky twist.