The Library of Congress has a huge amount of information on digital content formats and the factors that affect sustainability. Anyone who has lost (or almost lost) a file because it was stored in an unsupported format (i.e. an old MacWrite file) will find this Web site fascinating. The discussion deals with still images, sound, moving images, text, Web archives and generic formats. Most of the discussion is very technical, but not so technical as to make the information unusable. This section of the Library is part of the National Digital Information Infrastructure.
One example of the highly useful information is the Digitization Guidelines. The Web site includes a Podcast and slides. Although some of the Websites get bogged down in bureaucratic jargon, if you work your way through all the levels you can find some interesting questions and their answers, such as "When seeking to acquire a body of digital content with the intention of sustaining it for the long term, which formats are preferred or acceptable and why?"
You may also be interested in the Global Digital Format Registry. The GDFR is a collaborative project of the Harvard University Library, NARA and OCLC with funding generously provided by the Andrew W. Mellon Foundation.
There is a lot of practical information such as "E-mail should be saved and managed just like any other important digital file. Save important personal e-mail on a hard drive or storage disk as simple text files, making sure to capture the header information. Ask if your employer has a policy about saving work-related e-mail. You may also print out important e-mails."
The amount of information on this series of Websites is astounding.