Butler University Libraries has a Reference wiki:

WikiRef is a collaborative review of databases, books, websites, etc., that are part of the collection of Reference Resources available at or via the Butler University Libraries. It functions like a Reference User’s Group that facilitates discussion between and the empowering of reference users.

Butler librarians, faculty, staff, and students are welcome to add their comments about any reference resource we provide, including how useful you find it and what classes it may apply to. Please only delete or change text if it is factually incorrect or unprofessional in deportment. You are also welcome to add additional reference resources that you have used at Butler.

And right there on the front page, it encourages faculty, staff, and students to add comments. Talk about building a reference collection with collaboration, which should contribute wonderful things to the learning community. Good stuff.