Have other people done this? Probably. I myself have started this from reading Edward Copeland's post on upcoming blogathons, and indeed stealing his links. (And Andy Horbal's as well.) (Plus any other blogathon indexers I can find: FilmSquish offers a particularly complete compilation - going back to the beginning, getting a few I missed; Piper at Lazy Eye Theater keeps a calendar in his sidebar as well.) But I am going back and putting in as many as I can find. I need a way to keep track of these things a bit better. (This is obviously a work in progress: one for the sidebar. Also, to be updated with new blogathons as I discover them, and fleshed out with any comments or additional links I decide to add over time. For example, adding the actual blogathon pages to the announcements, as they come in. And, I think, adding links to my contributions: not because they're anything special, but as a way for me to find them in a hurry.)
January 14, 2008: Val Lewton blogathon, hosted by Michael Guillen.
January 1-5, 2008: And start the new year with an Opening Credits Blogathon, at continuity.
December 27-30: End the year with an Endings Blogathon, at Joe's Movie Corner. Here it is.
December 16: in honor of its 24-7 presence on the airwaves, a day for It's A Wonderful Life, at Cinemathetics. The day has arrived - here it is.
December 2-8: Short Film Day at Ed Howard's blog. Make that week, in conjunction with Culture Snob.
November 19: Here's one I almost missed: A Queer Film Blogathon, at Queering the Apparatus.
November 15-22: work up a Thanksgiving appetite with a week of Kurosawa movies at Film Squish! Main page here.
November 10: A Bob Fosse fest at Forward to Yesterday. Showtime.
November 7-9, 2007: Film and Faith blogathon at Strange Culture. Posts here.
November 6-11: Comedy blogathon at New Critics - for any format: films, TV, books, stand up, you name it...
October 22-26: The Broken Projector's Double Bill-a-thon - write about 2 films for the price of one! Twice the fun!
October 17: Honor Montgomery Clift, at Film Experience. Happy Birthday, Monty.
October 12-21: Close-Up Blogathon, at The House Next Door. Going strong.
September 24-30, 2007: A whole week of Bunuel at Flickhead. And here it is.
September 21-23: William Wyler honored at GoatDog. Articles here.
September 7-10, 2007: Slapstick Blogathon at Film of the Year. Read it Here.
August 29: Lee Marvin blogathon, picked up in progress.
August 27-29: Bizarro Blogathon, hosted by Piper at Lazy Eye Theater. Which sucked royally. I am far too serious for this sort of thing, though careless readers may think this WC Fields post is a joke.
August 5: John Huston blogathon, from Sophomore Critic. Announcement here. I have a post about Beat the Devil (and Huston's adventure films generally) up.
August: In a twist on the format, but worth mentioning - Damien at Windmills of My Mind promises 31 days of Spielberg: "I will view each and every available Spielberg film, write a corresponding piece about it and then post them here on my blog, one a day throughout the entire month of August (31 days, 31 posts)" sez he.
July 24, 2007: Monster Squad-a-Thon, at DVD Panache. Contents of said blogathon, here.
July 13, 2007: Not sure how this happened (vacation! yeah, that's it!), but I somehow missed the Friday 13th Blogathon at Final Girl.
7 July, 2007: The Performance that Changed Your Life - at All About My Movies. Read it here.
June 29-July 9: John Ford - in French, but c'est la vie. And here is the link.
June 21-25, 2007: Film Music - at Windmills of my Mind. Beginning a day early!
June 20-24: Ambitious Failure blogathon, at Savage Art - already underway.
June 12: Action Heroines at Film Experience. (I'm stealing most of these new links from Edward Copeland - that's where I stole most of the old ones, too.) Here it is. And as promised, my Brigitte Lin appreciation.
June 11: Sneaking in late - it's a Grease 2 Blogathon Chezzzz Moviezzzz. Underway.
June 8-10: Ghiblog-a-thon hosted by Joe's Movie Corner, dedicated to all things from Studio Ghibli. (Expanding on Quiet Bubble's Miyazaki blogathon from last year.) Opportunities here for synergy - repurpose those Princess Mononoke posts for the Action heroines blogathon a couple days later! Here's the Ghibili-a-thon HQ.
June 4-8, 2007: Simpsons - at Esoteric Rabbit - and here it is.
May 25, 2007: Star Wars - celebrating the 30th anniversary, at Edward Copeland's place. The host of contributions are indexed here.
May 16-20: Misunderstood Blogathon, at Culture Snob.com. Underway. I contributed another essay on Inland Empire. (Probably not the last thing I'll write about Mr. Lynch.)
April 23, 2007: Shakespeare on Film with Peter Nellhaus - underway here.
April 9-11, 2007: John Carpenter blogathon at Lazy Eye Theater (in honor of the release of Grindhouse). Up and running!
April 8, 2007: Mobathon announcement at the Boob Tubers. And the Mobathon itself.
April 5, 2007 (and forward): Trashy Movies - at Bleeding Tree. Underway, here.
April 1, 2007: White Elephant Blogathon at Lucid Screening - Home Page here
March 30-April 2, 2007: Favorite Screenplays at Mystery Man on Film - Table of Contents
March 23-25, 2007: 1927 Blogathon at Goatdog
March 21, 2007: Virgin Stripped Bare By Her Bachelors at Hell on Frisco Bay - the blogathon itself is here.
March 5, 2007: Kieslowski blogathon at Quiet Bubble
March 1-4, 2007: Billy Wilder at Filmscreed. My link to it has some discussion of The Apartment.
February 16-19, 2007: Jim Emerson's Contrarian blogathon, which I contrarily left out when I first posted this.
Feb 14: Lovesick Blogathon at Lucas McNelly's site - and, the thing itself.
January, 2007: Unspoken Cinema - contemplative cinema: still active! (Also - as Andy Horbal mentions in the comments - the sidebar at this site contains links to a great many previous blogathons - up to Andy's criticism blogathon, conveniently enough.) I contributed a couple posts - here's the tag.
December 3, 2006: Film Criticism at Andy Horbal's No More Marriages. I have two related posts: favorite critics, and five more.
April 5, 2006: Roger Corman.
March 3, 2006: Robert Altman, at the House Next Door. I wrote two posts for this - one about Altman's influence on me as a movie fan; the other a long geeky thing about McCabe and Mrs. Miller.