For "finding datacenters", traceroute is useful. You can just pick some websites and see where they host. For example, is seems that pinboard.in is hosted at http://he.net/colocation.html, Fremont 2, or at least that is where I am being routed.
Aside: back in the early days, a lot of YC startups hosted at HE. I think it was one of the first JTV colos, actually.