Future dead media

I love The Dead Media Project. It’s a shrine to scores of proprietary formats that have passed on to their reward.
It’s also a warning to us all. Today’s proprietary media with very near-universal adoption (e.g. Flash; Microsoft audio, web, and document formats; Real Audio; PDF) may be useful in specific applications, but information encoded in them may not be readable in the future. And you have no control over what it may cost to read them in the future.
It’s a powerful argument for using text; separating content from format; and keeping your markup as simple, structured, and standard as possible.
Of course you still have to worry about the life span of your content management system, database files, physical media, and backups.