Use this for Apps/Scripts/Libraries/APIs that:

 1. Require/use obsolete API's.  <sup><sub>EG: Stack Exchange API version 1.0</sub></sup>
 2. Operate on/for sites or features that no longer exist.
 3. Have websites and/or source-code that has disappeared and is not salvageable.
 4. That the owner/developer otherwise indicates is obsolete and/or serviceable.

See also: https://stackapps.com/questions/7983/what-should-we-do-about-dead-listings