Random House is following rivals by opening an electronic shop, for "younger tech-savvy" readers.
It will sell books of between 20,000 and 50,000 words and include titles on popstar Bjork and one called Hair! The Quest to End Baldness.
Jonathan Karp, publisher of the unit, AtRandom, said initial titles would be "too long for magazines but not door-stopping" books.
"Nobody knows where its going," he said of the trend. Electronic books and reading online could "go the way of the Walkman or the eight-track tape. Nobody knows."
Titles will be sold as digital books or in single copies printed on demand. They will also be sold at outlets like Amazon. Some 20 modern books and 100 classics will go on sale from early 2001.
It is the second big US publisher to go electronic after Time Warners May launch of iPublish.com.
Lighting Source, the print-on-demand firm, ran off its millionth book in July. Stratus in Thirsk, Yorkshire, was the first UK publisher to offer in-house digital books on an IMB Inforprint laser printer (PrintWeek 14 January).
But Stephen King bypassed publishers altogether, putting his new 10-chapter book, The Plant, on the Internet asking $1 a chapter to download. It has made $116,200 so far.