At this moment I use:
- Dropbox for managing books (sorted in folders by topic) and summaries. It resolves an issue with sharing ebooks on all my devices.
- Evernote for managing notes and web clipper for read it later in a subway.
- Bookmarks for saving links to interesting articles.
- Google docs for sharing documents and collaborative editing.
- Goodreads for managing to-read list and discover new books.