What this (very good) post calls the "condo" tier is what the hosting industry calls "co-lo" or "co-location". Search that term and you'll get more options than you can probably wade through. The "rackspace" option (biggest name for good quality mid-tier sized setups) is http://www.equinix.com/

Huffington Post, Gawker, BuzzFeed, CafeMom and AdMeld all co-lo with http://www.datagram.com/, most of them are within a few feet of each other.