Openstreetmap, a global map for worldwide insight
OSM is also one of the few remaining websites on the internet that allows bring-your-own OpenID 2.0 login!  I put together a tiny personal OID server (plug: <a href="https://gitlab.com/rendaw/oidle" rel="nofollow">https://gitlab.com/rendaw/oidle</a>) and OSM was one of the only public places I could test it...