I just stumpled upon this tool which is (for me) a very good companion to XnView:
Exifdropper
http://fliggs.wordpress.com/exifdropper-help/
It needs the Exiftool from Phil Harvey and gives you the ability to tag your pictures directly from the browser without going through the menus.
I just use the provided "Variable Preset" and it is great for tagging keywords.
Give it a try and maybe sometime we have this feature in XnView (or am i to stupid to use it at the moment...??????)
Jimmy
Exifdropper: drag n drop IPTC/Exif Tagging with XnView
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