After searching a lot in finding the best cross-platform organizer & viewer around, I finally (ALMOST) found it.
It is called XnView MP and it has an ultra-fast thumbnail manager, viewer - it supports a very big number of file formats for thumbnailing/viewing - including InDesign(!) - a top-notch cataloging, the best & fastest batch convert which I could find and... <insert your advertising of choice here>.
However there is a problem:
When we add/edit the metadata for an image (specifically the caption) in its IPTC/XMP editor (Ctrl+I), the text isn't shown with the Live Captions feature of InDesign CS6.
We discuss with the developing team of XnView MP and they are very responsive and want to fix the problem but we don't know (yet) from where InDesign reads its metadata.
Some more technical info to describe the problem:
1. The files are TIFF (LZW packed) files.
2. If we open the file in Photoshop, press Ctrl+Shift+I in order to bring its IPTC editor, the caption entered with XnView shows up correctly in the Description field.
3. If, after the step 2, we close the editor with 'Ok' do a 'Save As' in Photoshop and overwrite the file, the caption will appear correctly in InDesign.
4. If, after the stpe 3, we (re)open the image in XnView MP's IPTC editor the caption is there.
It seems that Photoshop does something behind the scenes and fill the area from where InDesign reads it.
Does someone know from what fields InDesign reads its info for Live Captions?
I don't really have an answer for you - I guess it's up to them to figure it out.
Sorry I can't help any further.