Booktype is an open source program for creating ebooks and preparing them for distribution on Kindle and iBooks. Booktype is designed for collaborative use by a group of writers. You can update your books and redistribute them even after your initial publishing date.
Booktype, the open source publishing platform. from Sourcefabric on Vimeo.
To clarify, Booktype is not a service it's an open source program that you can download and install on your own server. If you have the skills to manage it, Booktype could be a good in-house solution for digital publishing.