Is there an open source alternative to "Adobe Digital Editions"?

Solution 1:

.acsm can only be used with Adobe Digital Editions and stands for Adobe Content Server Manager.

For more information about Adobe Digital Editions please see http://www.adobe.com/products/digitaleditions/faq/

_{Side note (may not be generally applicable to Digital Editions users): Stated in the agreement (may be of concern in making a program to access .acsm ) for Adobe Content Server section 11.1 you agree not to:}

_{(d) obtain or attempt to obtain any materials or Information through any means not intentionally made available through the Services;}

_{Interpret this as you will, I will not give you legal advice.}

Solution 2:

You can also use OverDrive which is a fairly reasonable ebook reader. You need to put in your Adobe ID to register it, and after that, it will open .acsm files and download the relevant ePub for you.