Photonator is a free alternative to Apple's iPhoto and the features it offers are very similar. You can import your photos from any camera, drive or disk. Photonator allows you to organize them by the typical criteria, ie date, person, location or more. However the added plus is the use of tags. Create as many as you want and use them to keep your photos organized your own way. Just like in iPhoto, you'll also be able to export to web, CDs or email.
We liked the fact that Photonator supports HDR images and the panorama tool is really cool to handle larger images. However on the whole the interface looked rather disappointing and doesn't compare to the sleeker latest version of iPhoto. We did also notice some slowdowns when using the application.
Photonator is a free alternative to iPhoto with tag management and HDR support.