Originally posted by jatrax GIMP can easily replace Photoshop, it cannot replace Lightroom. Most discussions such as this focus on the image processing, which IMHO, is a distant secondary consideration to image organization, keywording and search & retrieval.
This. Apple kicked off this genre of software with Aperture, and it was brilliant. Adobe then created Lightroom as their spin on the subject. With Aperture now abandoned, there aren't many alternatives to Lightroom for organizing a photo library and workflow.
There is a program on Linux systems called Darktable. (It's available for other platforms but, like The GIMP, it's native to Linux.) It seems to be an attempt at an Aperture or Lightroom type of program. I've dabbled with Darktable a couple of times, but it seemed awkward, limited and counter-intuitive (especially running it on a Mac), and there's limited help available -- mainly in the form of Youtube tutorials. I'm not sure it's ready for prime time. It's free, though, so there's no harm in giving it a spin.
I grabbed a program off the Mac App Store called iSmartPhoto. It's a photo browser that seems to include many of the management tools of Aperture or Lightroom, but without any editing or adjustments. Library management is its thing, but it also lets me select a photo and then open it with any one of a whole list of other programs -- any program Mac OS X recognizes as accepting that type of file. So... I could use iSmartPhoto to manage the library and then call on The GIMP, or Acorn, or CameraBag 2 (which is quite good) for editing and adjustments.
Bottom line: It's possible to live without Lightroom, but you have to beat the bushes and find a set of programs on your chosen platform to perform its various tasks. There is no other convenient package that does everything it does.