The
Sigil ePub editor can be found at:
https://www.mobileread.com/forums/forumdisplay.php?f=203 It is a Cross-platform (Linux, Windows and OS X) tool.
The
Calibre conversion and reading tool can be found at:
https://www.mobileread.com/forums/forumdisplay.php?f=166 Please post any Calibre specific questions and comments in that forum instead of this ePub one. Note that Calibre now includes a full editor that rivals Sigil although the approach is a bit different.
Writer2ePub is ePub creation tool and can be found at:
https://www.mobileread.com/forums/forumdisplay.php?f=230 An OpenOffice extension to create ePub documents with OpenOffice.
EPUBReader is an ePub reader and can be found at:
https://www.mobileread.com/forums/forumdisplay.php?f=211 An add-on designed to read books in ePub format from within the Firefox and SeaMonkey browsers.