Msg#: 3237819 posted 7:52 pm on Jan 31, 2007 (gmt 0)
Adobe Acrobat is the best software to use to create the eBook. Although many programs support PDF export, to annotate, create bookmarks, or add hyperlinks - that is, click in the table of contents, go to that chapter - you will need at least Acrobat Standard.
Browsers will use helper apps to display the PDF in the browser, even if you change the file extension. You will need to feed the file to the browser with a munged content-type header to force it to download. Recently discussed here [webmasterworld.com].
Also touched on in that thread is a method of securing the download. You will need php, perl, or other server-side scripting skills to do this, as well as connect ot a payment processor - which answers your question, there are no free canned applications you can get for free to do this.
However I've programmed this exact same scenario quite a few times. :-)