calibre-ebook
[img]http://calibre-ebook.com/site_media//img/home-feature.jpg[/img]Scheme Maker
[img]http://schememaker.sourceforge.net/images/screenshot.png[/img]Virtual Moon observation
[img]http://ap-i.net/avl/_media/en/screenshot/double_window_uk.jpg?w=400&h=300&cache=cache[/img]