I picked up some pretty haggard looking prayer flags a little bit ago from a dumpster. They were pretty worn, but I felt like I couldn't just leave them there. So, I washed them a bit and now they are hung across my room.
I've done a little bit of research on them as well. Apparently, the traditional flags come in sets of five, with each color symbolizing a different element. "Blue symbolizes sky/space, white symbolizes air/wind, red symbolizes fire, green symbolizes water, and yellow symbolizes earth. According to traditional Tibetan medicine, health and harmony are produced through the balance of the five elements."