  We present our attempts to detect magnetic fields in filamentary large-scale
structure (LSS) by observing polarized synchrotron emission emitted by
structure formation shocks. Little is known about the strength and order of
magnetic fields beyond the largest clusters of galaxies, and synchrotron
emission holds enormous promise as a means of probing magnetic fields in these
low density regions. We report on observations taken at the Green Bank
Telescope which reveal a possible Mpc extension to the Coma cluster relic. We
also highlight the major obstacle that diffuse galactic foreground emission
poses for any search for large-scale, low surface-brightness extragalactic
emission. Finally we explore cross-correlation of diffuse radio emission with
optical tracers of LSS as a means to statistically detecting magnetic fields in
the presence of this confounding foreground emission.
