Bookworm, “an experimental platform for storing and reading ePub-format books online,” is closed as of March 31, 2012.

Developed by Threepress in 2008, and brought into O'Reilly Labs in early 2009, Bookworm has been an interesting and useful experiment—we learned a lot, and heard from users that they appreciated the service. The ebook ecosystem has changed dramatically in the past two years, and many good alternatives have emerged, so we’ve concluded that it’s time to end this particular experiment. Thanks to all who participated in the three years that Bookworm helped make ePub a reality for readers.

Here are ePub reading environments we think are good alternatives for Bookworm users:

Aldiko

Booki.sh

BlueFire Reader

EPUBReader

iBooks

MegaReader