What are these bars on an F-16's nose?
These are antennae for the IFF (Identification Friend or Foe) system.  IFF is a system to help distinguish friendly aircraft from unfriendly ones.

This particular antenna arrangement is used on only a couple of F-16 models. The first was the F-16 Air Defense Fighter (ADF) version. This model was converted from the F-16 Block 15 for use as a fighter interceptor for the US Air National Guard. A total of 271 F-16A and F-16B aircraft were upgraded to this standard between 1989 and 1992. One of the modifications made during the conversion process was installation of the Teledyne/E Systems Mk.XII Advanced IFF system, given the designation APX-109. This system included four antennas, often nicknamed &quot;bird slicers,&quot; placed in front of the cockpit canopy with additional antennas on the bottom of the inlet.

From: http://www.aerospaceweb.org/question/planes/q0286b.shtml