These are a few utilities that have been useful in development of the tools. The .grc files can be opened and used with gnuradio-companion.
file-player.grc: This is a tool that simply reads a file and plays it over the USRP and then listens on the same antenna. This allows you to view the signal that is stored in the file as if it were being broadcasted by another source.
test_signal.grc: This is a simple tool that broadcasts a sine signal and records it to verify that the USRP is functioning properly.