muCommander is a cross-platform file manager with a dual-pane interface that features support for FTP, SFTP, SMB, NFS, HTTP, Amazon S3, Hadoop HDFS, Bonjour/Zeroconf, email attachments, archives in many formats (including Zip, RAR, 7z, GZip, Tar, Bzip2, ISO, NRG, AR, Deb, and LST), bookmarks, credential management, themes, multiple windows, full keyboard control, and many configuration options. It is available in 23 languages.
X File Explorer (Xfe) is a filemanager for X. It is based on the popular, but discontinued, X Win Commander. Xfe is desktop independent and is written with the C++ Fox Toolkit. It looks similar to Windows Commander or MS-Explorer, and is very fast and simple. It features file associations, the ability to mount/umount devices, a directory tree for quickly changing directories, the ability to change file attributes, automatic registry saving, the ability to view/create/extract compressed archives, and much more.
Alexandria is a GNOME application to help manage a book collection. It retrieves book information (including cover pictures) from several online libraries, allows you to search for a book (either by EAN/ISBN, title, authors, or keyword), can import and export data into ONIX, Tellico, and EAN/ISBN-list formats, generates Web pages from your libraries, allows marking your books as loaned, saves data using the YAML format, features an HIG-compliant user interface, shows books in different views that can be filtered or sorted, and handles book rating and notes.