Geeqie is a lightweight Gtk+ based image viewer for Unix operating systems. 

Main features
  o EXIF, IPTC and XMP metadata browsing and editing.
  o Interoperability, easy integration with other software.
  o geeqie works on files and directories, there is no need to import images.
  o Fast preview for many raw image formats.
  o Tools for image comparison, sorting and managing photo collection.

History
  Geeqie has been forked from gqview project, because it was not possible to
  contact gqview author and the only maintainer. Geeqie projects goal is to move
  the development forward and also integrate the existing patches. 

WWW: http://geeqie.sourceforge.net/