  Universal factors associated with the emission of a soft boson in gauge
theories and gravity, formulated in the light-cone gauge, are presented. The
inverse-soft method, for constructing higher-point amplitudes from lower-point
ones, using these factors is reviewed. These ideas are then examined in
(light-cone) superspace and applied to both the N=4 super Yang-Mills and N=8
supergravity theories. One highlight is a compact result for the quartic
interaction vertex in N=8 supergravity, a crucial ingredient for finiteness
analyses.
