Just about every publishing company has its own website, which you can find without too much trouble: the ones that I've listed here are those which seem particularly useful to me, or particularly interesting. If you have your own personal favourites and don't see them here, do let me know so that I can add them to the list.
The Abbeville Manual of Style is exquisite. Read it every day.
Behler Publications is an independent publishing house founded and run by Lynn Price, who comments frequently here. Behler used to have a Blogspot blog but has now turned to the dark side and gone over to Wordpress. Both blogs are worth trawling through, as they're dense with information.
Bluechrome, independent publisher of lovely literary fiction, short stories and poetry, blogs. Which is just as well because lovely though Bluechrome is, I can barely read its website because of the colours of the text.
Ebury Publishing has a blog, a balcony garden, and a lot of lovely books. Each time I see pictures of the balcony garden I wonder how long it'll be before the whole thing plunges off the face of the building, ripped away by the weight of all those sodden grow-bags. But the strawberries do look wonderful.
Editorial Anonymous is the blog of an American children's book editor who blogs almost daily about the publishing business, what editors and agents want to see from writers, or cake. It's a winning combination.
Editorial Ass is the blog of a New York-based editorial assistant who writes about her work and her life. It's funny, informative and insightful. Lovely.
Little, Brown's blog is little more than a catalogue of its forthcoming titles and various author events: I would do so much more with it, and I'm afraid it's a missed opportunity for them.
Me And My Big Mouth is Scott Pack's blog. You'll find lots of reviews there, lots of talk, and a fair amount of publishing information and gossip too. Mr Pack used to run Waterstone's, and now he runs The Friday Project, which is an imprint of HarperCollins.
Monday Books publishes mostly non-fiction with a slant towards politics, satire and memoir, and all of the Monday Books titles that I've read have been bloody brilliant.
The Penguin Blog has some interesting content related to its books and I like it: but I found little there concerned with writing or publishing.
Picador, which is part of Pan Macmillan, blogs.
Salt Publishing specialises in publishing anthologies of short stories and poems, and I've not yet read a bad collection from them. Gorgeous books, the lot of them.
Snowbooks. Beautiful books, lovely people, and a great blog.
Two Ravens Press publishes lovely literary fiction, and has a very interesting blog.