According to the techies, QR codes were going to revolutionize everything. What is a QR code? Exactly. The little dotted squares that let you go straight to a website have been pretty duddy, to say the least. That is, until street artist Nether and housing activist Carol Ott got ahold of them and started placing them on the sides of vacant buildings. Scan the code and go straight to Ott's Baltimore Slumlord Watch blog, where you can find out not only who owns the building but in whose district it is located.