WMG: Ore no Imōto ga Konna ni Kawaii Wake ga Nai

The ticket to America wasn't what Kirino wanted to show Kyousuke as part of the last life counseling session.
Kirino tells him there's something else in her closet that was way in the back that Kyousuke didn't know about, and that she will finally show him because of everything else he saw in there. She opens her closet, but the box with her album in it falls out- she does not hand it over to him. The ticket may have just fallen out coincidentally. Who's to say that's that Kirino wanted to tell him?
  • It's actually revealed in the light novels, but the photo of young Kirino is a big part of it. The album contains more of such photos and her past exam results, showing that Kirino has worked crazy hard to get to her current top student, track star status.

Kirino is bisexual.
  • Do I really need to explain this one?
    • Ahem. It's called wild mass guessing =P

Like Siscalypse, Stardust Witch Meruru will eventually be made into an actual anime.

Kirino has a crush on Kuroneko.
It seems that Kirino's way of dealing with affection, especially of taboo sort is to deal its target like dirt. See how similar her banter is with Kyousuke and Kuroneko, and she is shown to use her vitriolic attitude to cover up her affection and possible romantic feelings towards her brother. Wouldn't the other major target of the same attitude be possibly also be a target of similar hidden feelings?

The Akagi siblings will star in a Spin-Off named "My Little Sister is Cute"
Less a WMG than speculation based on a comment in the Episode 13 DVD Commentary, which showed quite a nice dynamic between the two, and specifically teased a Spin-Off with that name. I'll go a bit further and say that the DVD Commentary itself was a test case to see how the reaction is in the community—if it's positive, they get their own manga or something.

Kirino and Kyousuke are Not Blood Siblings, and the proof is in that album she was going to show him
This has already been teased in an If route of the PSP Visual Novel. It's been mentioned on different forums that with the current climate in the wake of the recent anime content bans, the only practical way to end the story would be either an ambiguous ending like the Episode 12 Good End, Kyousuke ending up with one of the other girls (which can never be ruled out as a possibility, but seems unlikely considering how Volume 8 ended), or Kyousuke and Kirino ending up unrelated and starting a romantic relationship. It's already been shown that, although the PSP game isn't canon, it has foreshadowed developments in the Light Novel, like the development of Kyousuke and Ayase's relationship down to specific lines of dialogue and Kyousuke going out with Kuroneko. They've already shown pictures of Kirino and Kyousuke as very young children in a few of the anime's openings, which directly contradicts the If route. However, this doesn't rule out the possibility of Kyousuke having been adopted before Kirino was born, and the album may have something like Kyousuke being nursed by his real mother to prove it.
  • This would help explain her unhealthy obsession with Kyousuke. Sure, siblings can get a bit jealous when they hang out with members of the opposite sex around the teen years, but Kirino seems to take it to extreme levels.
    • current information from volume 11 seems to imply that she used to love him in normal sibling sense but due to reasons her feelings turned in on themselves and festered uncontrollably, it also turns out she DOES project on to the little sisters in the games, subconsciously anyway
This is another universe that Haruhi Suzumiya made.
One day a certain Reality Warper said "You know, my life is great and all, but what I'd REALLY like is a world where I was in some sort of incest love." So she destroyed that world and made this one, where she's on the fence about liking her brother. In this world, Kirino is Haruhi, Kyousuke is Kyon, Kuroneko is Yuki, Manami is Mikuru, and Saori is Itsuki.
Kyousuke and Ayase were originally supposed to be siblings.
Look at their character designs: same hair fringe, same eye color, and then there's the sudden "attraction-at-first-sight" they had in the beginning. I'm guessing that the author drafted a twist like that in the beginning and when you think about it made sense: Kirino becomes an adopted sister—opening her up for a proper romantic ending, and Kyousuke gets to develop a more fraternal relationship with a girl that was originally set up as his first love. It looks nice. He then talked to the artist about it, who then came up with a character design for Ayase to foreshadow this future twist. This then explains her vague resemblance to Kyousuke. But, somewhere down the drafting stage, the author decided against it because this would have diverted attention from the series' main focus: Kirino. So he dropped the idea, nuked it completely by turning Ayase into a yandere, but still decided to keep Ayase's character design simply because it looked too good not to use and as a nice little reminder to himself of what could have been.
Ayase cuts ties with Kyousuke after he turns her down.
I don't know about anyone else, but that "Sayonara, Onii-san" she gave him sounded extremely final to me. Due to her Yandere nature she probably still wants to be with him, but she understands that will never happen. Therefore, to avoid hurting herself even further she stops associating with him altogether. Note that while Kuroneko takes Kyousuke dumping her about as badly she still continues to hang out with him and Kirino. Ayase does not even appear in the show after episode 12 except for a short flashback of her first meeting Kirino. This may be due to plot restrictions but I still take note.
Learning about Kyousuke and Kirino's relationship drove Manami insane.
Perhaps not to an incredible degree, but something in her head definitely snapped. Let's look at the reality. She and Kyousuke have been best friends since they were young kids. They walk home together practically every day. He has told her multiple times that she is extremely important to him and that he doesn't want her to change. His expressed desire is to have a normal life, and she is about as normal as can be. Pretty much everyone they know is convinced that they are in love with each other. He even is, just not in the way she wants him to be. Looking at all of this it's safe to assume that Manami thinks he is in love with her, just too dense to recognize that she is also in love with him. Then for her to realize that this guy is in love with his own younger sister, a girl who in Manami's mind (and in reality) is rude, condescending, and generally bitchy, and doesn't even bother to tell her, there's no way that didn't have an effect on her. I support the siblings' relationship but I can't help feeling incredibly sorry for Manami here. Think about the irony. He sees his love interest Manami as family, while he sees his family Kirino as a love interest.