What is the purpose of the vortex generators located right in front of the Boeing 737's windshield?
Apparently, they are there to reduce the cockpit noise. From b737.org.uk:
Notice the 10 small vortex generators above the radome. These reduce the cockpit noise from the windshield by 3dB.
According to this document, the VGs, along with other improvements like damping/insulation changes, window frame improvement and ECS improvements contribute to a total noise reduction of 3 dB (at 35k ft and Mach 0.78). Though their exact impact is unknown, the reason for VGs are there is to reduce cockpit noise.