Uh, this is a topic I'm also very interested in (what other people use and why).
Formerly i used Adobe Bridge (for tagging, renaming and so on), i think it's really powerful, but i was always wondering, if there wasn't another alternative to that.
If i remember it right, it made for every raw file tagged another .xmp file with the additional information, which i counted as a con, but anyways i was quite satisfied with it..
"Formerly" because i stopped tagging some year or two ago, which may have been not that good idea