AOFlagger
RFI detector and quality analysis for astronomical radio observations
...I believe that the AOFlagger is the best available flagger, both in terms of accuracy and speed. It has been succesfully used on several interferometric telescopes, including LOFAR, WSRT, VLA, GMRT, ATCA and MWA, and the single-dish telescopes Parkes and Arecibo 305m.
Besides the flagger, the software consists of tools to efficiently visualize data in different ways, such as plotting time-frequency diagrams and power spectra. It provides the programs rficonsole, rfigui, aoqplot, aoquality and more.