As a teacher in the 90's one of the new digital tools that I used was a digital encyclopedia on a CD. Encarta, from Microsoft, was one of the most popular multimedia encyclopedias (1993-2009)
"The standard edition of Microsoft Encarta included over 50.000 articles of information, which includes images, video and sound; the premium edition contained over 62000 articles, along with over 25000 images and over 300 videos. Microsoft Encarta also included an interactive Atlas, where users could view and see information from nearly 2 million different locations. The later versions of the Microsoft Encarta electronic encyclopedia included more complex multimedia content and a range of other features." http://microsoft_encarta.en.downloadastro.com/
There may be many reasons why Encarta and other digital encyclopedias no longer exist, but one reason is the development of Wikipedia.
Wikipedia has long been the bane of educators as students by the million use it as resource material for writing papers. As Wikipedia has mature over the last 15 years it has gained more respect and should not be shunned by educators.
In this TEDx talk Andrew Lih (The Wikipedia Revolution) invites a new generation to become editors of and contributors to Wikipedia.