I have found Yuletide one of the best places to find awesome Diana Wynne Jones fic, and there are some seriously fantastic stories there this year - some of which I suspect were written by some of you. (Including the one I received, which was AMAZING.) Anyways, I figured I would do a roundup here, in case anyone is looking for a story in their favorite Jonesian fandom!
The Problem with Being an Older Brother - Erskine, Venturus, and crazy wizard family dynamics
Sonatina for Unaccompanied Minor - An Awful story that is not in the least awful, with a very complex plot and about a million easter eggs for the attentive reader that I will not give away
Howl's Moving Castle
Three-Way Mirror - Three very different perspectives on Sophie
Ella's True Love - A very funny look at Howl and Sophie's relationship through a Mary Sue's eyes
Song - The development of Howl and Sophie's relationship through the course of the book, as seen by each of them
Subtle Attraction - Pre-canon Howl, out on the town
In Which Howl Adjusts His Crooked Heart - Howl and Calcifer immediately after Howl's Moving Castle
The Boy With The Thorn In His Side - Cat, post-Pinhoe Egg, observing his world and trying to find a place in it
Apple Vines - A beautiful story about Cat and his family, or lack thereof
Chrestomanci Training - Immediately post-Charmed Life, Cat and Chrestomanci have a heart-to-heart
Appearances - Also just post-Charmed Life, Julia and Janet find a way to bond
Rhinegold - Cat, Tonino, and Marianne have wacky Jonesian hiijinks on Conrad's world!
A Unicorn in Central Park - Chrestomanci crossed over with How I Met Your Mother. Yes, you read that right!
The End Is Where We Start From - The death of Amil. (OR IS IT?)
The Prisoner's Dilemma - Full disclosure: I wrote this one. Navis during the time of Kialan's trial.
The Last Free Soul of Dalemark - A fabulously complex metastory set in Dalemark's future, with all kinds of twists. Features the television production of Hobin's Way!
Fire and Hemlock
Letters from Afar - Drabble about Tom's letters to Polly
Come Away, Oh Human Child - Chilling (but hopeful) postcanon fic set during Polly's pregnancy
Truly, He Hadn't - Explores Tom's perspective over the course of canon
A Kind of Magic - Mordion and Kessala, pre-canon. Lovely and painful
Old Hands and New - I don't quite know how to describe this one without spoiling the premise! Futurefic about our new Reigners.
The Homeward Bounders
To Be Of Use - Joris, pre-canon, and his discovery by Konstam
The Ogre Downstairs
Growing Together - I love this one most because it was written for me, but also because it's awesome! A postcanon story involving a trampoline, a new kind of magical happening, and lots of complex sibling relationships.
And I think that is all of them - if I missed one, let me know and I will add it! (I did not include the Miyazaki-Howl stories, though some of them are probably just as awesome, mostly because I have not gotten down to the Hs yet in my Yuletide browsing.)
Edited: i_phianassa suggested that I link to the unfulfilled requests for New Year's Resolution stories, which is an excellent plan as well! Here is the New Year's Resolution page; there are unfulfilled requests for Howl's Moving Castle, Chrestomanci Chronicles, Dalemark Quartet, Dark Lord/Year of the Gryphon, Fire and Hemlock, Homeward Bounders, the Magids series, Tale of Time City, and The Ogre Downstairs. That has the potential for a whole lot of awesome fic!