Five pilots => Forty-some episodes => N billion fanfics.

Apply Sturgeon's Law. Apply again. And again. And again. And again.

Apply until you've completely flooded a dozen shopping complex parking lots with the discarded fics.

Done? Here's what you might end up with:
 

(In no particular order, because Composer's table system sucks. Unfinished fics are starred.)
 
Clouds and Lions torch (None) Clouds. Lions. Trowa. torch. You just can't go wrong. 
Anatexis Alexe (Various) An AU series exploring a world in which Mariemaia is dictator, Wufei her second-in-command, and the rest of the Gundam pilots either dead or missing. It's won some awards. There's a reason.
By the North Sea Sabina Tang (3+4, 1x2) I sincerely doubt that anyone who's been in anime fandom any length of time hasn't already read everything Sabina's written. But if, by some odd quirk of fate, you haven't, then /go/. Now. Blissful good!fic stupor awaits.
Vendetta for the Fey Hope of Dawn
(Rebecca Potter)
(None) *shiver* I don't usually care for shortfics in GW, but damn, I loved this. Dark, twisted, and oh so good.
Curing Homosexuality Erin Cayce (2x?, 1+2) Erin's fics run a gamut of flavors, but I think I like it best when she does nitty-gritty realistic. 
From Forever to Forever Quatre-sama (3x4, Various) Angst galore, and no one gets raped. No one gets beaten, even. In fact, lots of people actually get married -- with members of the opposite sex.
Shocking, huh.
Shades of Light Ryoko (1x4, 1x3, 3+4) Requited love. Try not to let it tear your heart out.
A Guide to Better Hugging Shusu (1x2) This is...sweet. Yeah, that's the word. Sweet, and very, very Duo.
What Keeps You Awake at Night? Tzigane and Yoiko (None) Here's something you won't find often on my rec pages -- humor fic. Pick up a thesaurus. Thumb to the entry 'funny'. Insert synonyms here. Now go read, and don't drink anything while you're at it.
Especially tea.

 
Inbound Telemarketing Lonewolf (1x2) After a childhood filled with death and destruction, Heero finally settles into a relatively peaceful career *snerk* 
Damn, I want his number.
*Bless the Beasts and Little Children Pyrephox (None) GW/Lycanthrope Leo crossover.
I have not the slightest idea what Lycanthrope Leo is, but for the sake of this fic, I'm glad it exists. G-boys as were-beasts.
Tears in Heaven Fractalforge (3+4) Trowa's being introspective. Not in a boring way, either.
Chiaroscuro Lorena Manuel (3x4, Various) AU Gundam schoolfic done right.
The Silence God Hilary Fox (3x4, Various) Q: When Gundam Wing meets Greek mythology meets Hilary, what do we get?
A: No sleep. Sore eyes. Sated sigh.
Niobe's Violets Ashura (1x2, Various) Past lives and superpowers. Another AU schoolfic, and another good one.
*Being Duo Maxwell Keelywolfe (1x2) Snarky Duo. Yummy writing.
*Asylum Spooks (Various) I quote the warnings: 'Duo POV. Complete and total AU, dark, self mutilation, depression, mental illness, visions,
auras, demons, supernatural, ghosts, torture, nonconsensual sexual content, lime, sap.'
Fun.
Companions of Fate Laekin (Various) /Long/ series. If you're looking to lose yourself in GW for a full 24 hours or so, this is the place to go. (The grammar errors seriously, seriously bug me, but they grow sparser as the story goes on and can mostly be ignored.)
*Prophecies Marika (Various) Uh, G-boys. AU. Magical powers. Y'know, the fate of the world rests on their shoulders and all that. They should be well used to it by now, ne?
(The latest installments can be found in the GW-fan archive.)
*Misreality Chibi_Angel (Various) AU hacker fic; kind of a Matrix/GW fusion. But not really. Oh, and Quatre gets to say 'fuck' a lot.
Mmmmrrr.
Fractured Adonis Phi (4+3, others) I would've /really/ loved this fic if it hadn't stomped over my heart in stiletto heels. As it is, I just love it. Even though it is friggin' depressing.
*Sainan no Kekka Quicksilver and Gerald Tarrant (None) It's long. It's good. It increases in weekly segments. Summary: After the war, the identities of the Gundam pilots are leaked, and the public responds. Badly.