EXIF headers, or rather the more important IPTC, will handle everything you could possibly want. It's supported in Photoshop (File Info) and any decent image application.

My favourite tool for touching this data (the last time I did that type of work) is EXIFER. Just do a search for it.

After many hours (days and days) of searching for image management software, Photools' IMATCH came right to the top with no equals.

I think a number of topics are getting meshd in this thread however. If you need to manipulate your images after you take them from your camera, you're still going to need to touch something like Photoshop or another editing package. Possibly multiple packages. Photoshop handles batch operations pretty easily and there are filters available to import both Canon and Nikon RAW files.

Bruno