URL shorteners still suck, but several URL shortening services have agreed to hand over the keys to 301Works in the event that a URL shortening company goes under. 301Works will be administered by Internet Archive.
Participating companies will provide regular backups of their URL mappings to the 301Works.org service. In the event of the closure of a participating organization, technical control of the shortening service domain will be transferred to 301Works.org in order to continue redirecting existing shortened URLs to their intended destinations.
As Andy notes, no Tinyurl.