Retro-computer gaming is growing more and more popular. Hundreds of thousands of people who played games such as ZORK, Lode Runner, Oil Barons, and Karateka are downloading games like these and reliving the 1980s and 1990s. (For younger gamers, it's a first-time experience.)
Old games made available for download on the Web are often referred to "abandonware." However, a lot of abandonware is not abandoned; it's just too difficult to enforce the copyright. LucasFilms works to keep its games off abandonware sites, but almost everything seems to pop up sooner or later. I even found an Atari ST version of my 1986 graphic/text adventure game at one site.
The games are largely forgotten, and many of the manufacturers, such as Sierra On-Line and Broderbund, are no more. Hence, the assumption that the games are free to all or "in the public domain." They're definitely not in the public domain; none of the copyrights have run out. A good number of games have been made available by their copyright owners, but not everything out there is in this category.
I mention this in part because there are probably readers who would enjoy some of the old games--those legitimately made available. To find them, Google "abandonware." I also mention it because I think that many of the oldies could be reintroduced and marketed successfully. In their heyday, these games had a short shelf-life because the market was constantly on the lookout for something new, and only those games that were mega-sellers were kept around. (Sounds a lot like the mass-market paperback market.)
Then there's the possibility of books becoming "abandonware." Thousands of out-of-copyright classics are now e-books (see Project Gutenberg). But I'm beginning to wonder how long it is before more contemporary books are given the reputation of being "abandoned," and start appearing at download sites. It takes some effort to scan and OCR an entire book (300 pages or more), but some people are willing to do it. And once the genie is out of the bottle--once a book's content is on the Web--you can't put it back. Pirated ebook versions of commercial bestsellers are already being sold on the Web and on eBay (The Da Vinci Code is just one example). If publishers don't try to stop this, I foresee hardcopy books going that way next. As soon as scammers are willing to put some work into intellectual property theft, we're done.