Personally, I think it's a conspiracy that every single conspiracy site has the same design. Dark background, huge multicolored fonts, badly scaled animated gifs, poor spelling, dodgy links to identical sites.... clearly the government is controlling the design of these web pages, keeping them at a level compatible with 1992 technology.
http://members.toa.../flashx.html#flash The rings look like they're all centered around weather radar sites, so the ring is actually an artifact of the radar generating the image. If you've ever been on a boat with a radar, you may notice that there's a lot of interferance and circular distortion in the part of the image near the transmitter. The radar has a hard time detecting very close objects, and gets scatter from rigging and tower structures nearby. (more scientific explanation:
http://www.weather...owthread.php?t=317)
Here's another explanation for a different type of radar:
http://www.hko.gov...dars/ring_3d_e.htm When you overlay data from multiple radar sites at different power levels on one map, you might get multiple "rings" centered around each site.