In Problem SleuthEdit
GameFAQs can be used not only by impatient players, but also, somehow, the characters themselves (PS and PI) with the aid of the Code Machine. Most notably, checking GameFAQS for cheats is the intended solution (the one not pursued by losers who have way too much time) to the plight of the four kingdoms. The FAQ which was used by Problem Sleuth was written by none other than Andrew Hussie.
GameFAQs first appears in Homestuck when Rose Lalonde is searching through it to find some walkthroughs on Sburb to help John Egbert figure out what he's supposed to do. Sburb is put under the genre of "Immersive Simulation", which would be pretty accurate as it actually affects the real world that John is in. Rose Lalonde writes an FAQ for Sburb, which she updates as she and John play through the game. John also writes part of it, explaining how he discovered a way to merge the codes of two captchalogued items to create a merged item. Rose's last update is written when she destroys her first gate. She then transfers the file off GameFAQs to a remote server located in the Furthest Ring, where it is later/earlier read by Kanaya.
The fates of the other Sburb walkthrough writers are considered in the Homestuck Book 2 commentary. On the first page of the book, Hussie notes that they all also wrote guides on Problem Sleuth (inferior to his own, of course), and muses on how their Sburb sessions turned out, other than obviously miserable failures. He then bets that "winnie the poop's was particularly catastrophic." Later in the book, he says that "SanctuaryRemix was probably killed before his session started, in a gruesome lathe accident. ChaosDemon crafted a small fort out of perfectly generic objects, and hid inside while weeping until the meteor came."
Each and every one of the guide writers listed in Problem Sleuth and Homestuck is a real GameFAQs contributor. Apart from Hussie (who is real, but not a GameFAQs contributor) and Rose (who is neither real nor a GameFAQs contributor), obviously. Many of them are quite notable.