For movies it would be definitely www.kutsite.com for me. Not really a blog it doesn't even have RRS. It's a Belgium site so everything is writen in Dutch. Not that they cover every movie but there reviews are usually on point.

For music I usually don't read blogs rather go to last.fm and listen to what the player comes up with. Once in a while I check www.hiphopmusic.com I really like the vlog they just start doing but like the title says it only covers one genre.

For books, I most often go to the public library and see what I come up with, sometimes I go to boeken.vpro.nl. Again not really a blog and also in writen Dutch. It might not be of great use to you, then again I'm sure I'm not the only Dutch guy here reading this blog.

"Flog," the "Fantagraphics "Blog,"" posts interesting comics stuff sometimes http://www.fantagraphics.com/blog/
"The Comics Reporter" joins "Journalista" as the best daily comics news source I know of:
http://www.comicsreporter.com/
If you also check the Comics Journal message board once in a while, you'll probably be covered on anything major going on: http://tcj.com/messboard/

For movies:
http://www.comingsoon.net and its sister site http://www.superherohype.com update early and reliably.

Similarly: Garth Franklin's http://www.darkhorizons.com/ (just stay away from the editorials)

There are other general movie sites I check, even though they have serious problems
Harry Knowles' http://www.aintitcool.com/ is revolting and frequently innacurate. Clint Morris' http://www.moviehole.net is better, but not by much; lately, it's come to resemble what Knowles does more and more.

For horror movie news, there's the trio of http://www.fangoria.com/ , http://www.bloody-disgusting.com/ , http://www.dreadcentral.com/ .
You will want to cautiously evaluate anything posted on the latter two, but I've gotten enough real information there that I don't discount them.

DVD release news: http://www.davisdvd.com/ , http://www.thedigitalbits.com/

One more for movies: http://www.boxofficemojo.com is the best website for box office news, though they've been slipping a little lately.

While I'm on the subject: if you're following an upcoming film, don't believe what you read about it in its imdb entry. That site relies on user-submitted updates, yet they seem to do little actual fact-checking and they're locking more and more of their content behind a paid subscription. The site is self-destructing in slow motion right now.

Great list, JC! I am amused by your description of AICN, also.

For the webcomics fans out there, I've found Comixpedia to have some interesting stuff. http://comixpedia.com/ I suppose it might be considered the "mainstream" webcomics news site, but it's not exactly a mainstream artform yet.

And it goes without saying that Slashdot is a fine resource. I stick to the gaming news mostly, but there's something there for geeks of every ilk. slashdot.org

The Buddyhead mp3 blog (http://buddyhead.typepad.com/) allows you to download the music they're ranting about, which is all I could ask for in a music blog.

My guide to the treacherously banal yet occasionally rewarding depths of pop culture is the Onion A.V. Club (http://www.avclub.com/), which includes three staff blogs of vague demarcation (they really ought to just combine it into one). Like the rest of the wonderful site, it's written from the perspective of several smart people who love good art, good trash, and everything in between. In fact, the blogs mostly seem to serve as an extension of the magazine, a catch-all for random news and personal musings that don't fit into the magazine's review/feature format. I recommend the whole site, really; even the crossword puzzle matches the tone, with 19th-century poetry up alongside the latest dirty words.

A similar blog focused solely on film is nerve.com's The ScreenGrab (http://www.thescreengrab.com/), which has lots of snippets of news on independent movies as well as snide reviews of trailers and reader-submitted Worst Moviegoing Experiences.