A large fraction of the baryons in the universe are in low density filaments and small groups outside of clusters of galaxies, and are quite difficult to detect. Over the past several years, my students and I have developed some innovative techniques for detecting low surface brightness synchrotron structures which are expected to probe these low density environments. I will talk about the detection methods and show examples of some interesting structures which are beginning to emerge. I will briefly mention the prospects in this challenging area with the new generation of arrays, including the EVLA, LOFAR, LWA, ASKAP, etc.