GitHub repository: mandrakos/coyote
Primary language: IDL
Description: The Coyote Library evolved from work David Fanning was doing teaching IDL courses and answering IDL questions on the IDL newsgroup. It is meant to be a well-documented library that demonstrates how to write solid (dare we say eloquent) IDL programs that are easy to maintain and extend. You can learn more about these programs and about IDL programming in general at David's web page, Coyote's Guide to IDL Programming.