Another good read: last fall's panel discussion on the profitability of ebooks and how this impacts the Big 6, over at Publisher's Weekly. Very nice info here on the ratio of profit to author versus profit to publisher in hardcover sales, wholesale ebook sales, agency ebook sales, etc. provided by Paul Aiken, executive director for the Authors Guild. Especially interesting when you've been reading Joe Konrath's blog for awhile (see previous post).
So, who are the Big 6?
The Big 6 in publishing are the six North American publishing houses that make the most money, year in and year out. Some of them are owned by even bigger powerhouses; for example, HarperCollins is owned by NewsCorp. (whose chairman of the board is Rupert Murdoch) (fyi, NewsCorp. owns Zondervan, the Christian publishing house, too).
As of February 2011, here are the Big 6 Publishing Houses (with links to their web sites):
Within each of these big conglomerates are a variety of imprints, whose names may be more familiar to you. For example, Harper Collins imprints include (full list here) Avon, William Morrow, and Walden Pond Press. To learn the complete listings of all the other imprints for the remaining Big 6, visit their sites (linked above).