A very old school bike, which we call a Long John. My dad rode one back in the 40's when he was working as a delivery boy. Goods are placed in the rack in the middle of the frame.
I have no idea what the grey rack thing is that the guy in the photo built. Just another unique bike on the bike lanes of Copenhagen.
Addendum: I saw this guy later carrying a bass. So he customised it to carry the instrument. Cool.