iDisk

 iDisk  (originally .Mac, but not a TLD) was Apple's cloud disk silo, that also provided web hosting and WebDAV support.

It was shut down for random company reasons, causing many site-deaths.

Articles
Articles mentioning problems with iDisk, especially relating to its shutdown
 * 2013-04-01 Hosting and Impermanence
 * 2006-04-28 Apple is holding my data hostage