A fan-curated wiki cataloging cases originally shown on Unsolved Mysteries, a television show that started in the late 1980's and ran in various forms until very recently.
This is a site that aims to collect and sort out information about some of the more unusual shortwave anomalies, like UVB-76, the more powerful numbers stations, the XM Whales, and other mysteries. Seems pretty solid, without much in the way of conspiracy, just necessary speculation.
International Center for Unidentified and Missing Persons. Accepts tips. Has a search engine which could be useful. Showing signs of being updated regularly.