GNU/Linux open photo tools
An Apple fan-boy tries to find a replacement for Aperture under GNU/Linux (Ubuntu) and, to his surprise, succeeds. ...and it's all open source/free software and runs on Windows if you're still stuck there.
The executive summary is that he likes The Gimp (like photoshop and also runs on Windows) for general photo-manipulation tasks, Raw Therapee (runs on Windows, too) for raw photo processing and Nautilus (GNOME's default file-browser/shell) for managing things.