[Worldwalker]

It does the job, anyway. There are a few publishers I actually care about, mostly due to the collectible nature of some of their books, so I just use a tag for them. Still, a dedicated source field would be nice, so the publisher field could go back to tracking publishers. Out of all the things calibre needs, though, I figure that's pretty far down on the list, and not worth even a formal feature request.

At some point, when I actually get my physical library sorted out, I'm going to add a tag for whether I own the book in physical form as well, and if so in what format(s). ThinkGeek sells a little barcode reader that could scan the ISBN ... hmm, I wonder if using that plus blank books would make it practical to use calibre to index my physical library as well?

@Kovid:

The advantage of a column over a tag (and the reason I'm using the Publisher column for that at the moment) mostly has to do with the PRS's Collections. When I have books from here, PG, Feedbooks, Baen, yadda, yadda, yadda, the number of added Collections cluttering up my PRS would start to really get out of hand (as if it isn't already, though not as badly as our friend with the 99 tags on his 17 books). If excluding tags from collections (via [] or whatever) is implemented, this will be much less of an issue.

Isn't there some form of source/distributor/etc. field in the epub standard? If so, having access to that through calibre might be a Good Thing.