Any single service or provider is unreliable, and what is needed is not a breadth of services (like the sort of service one or two techies seized by a HN-related enthusiasm might start running) but a depth in time of services - long-term services.

Currently, I back up URLs I care about or link on my site to ~3 places: the Internet Archive, WebCite, and my hard drive ( http://www.gwern.net/Archiving%20URLs )