some guesses:

-We learned that the WT Accepted Test and the Wise Ones' version use similar devices. Both connect to an individual person's relation to time. Both are in cities made by Aes Sedai.
Is there more of a connection between these devices? Between the two groups (WO & WT), organizations that actually have quite a lot in common? The WT terangreal needs to be channeled at, but the other exists in a deserted city. The Rhuidean terangreal acts like a Portal Stone when it doesn't work right. Can it also send people to other places? Between the WT Accepted and AS terangreal, the portal stones, and that Rhuidean ternagreal, we have quite a lot of objects that bend both time and space.
Finally, note that Far Madding and The Stone of Tear are also AS-made. Why have we never heard about major efforts to catalogue the "storehouses" of Tear and Rhuidean?

-Taim's introduction in which Bashere doesn't recognize him.
The explanation - "I shaved" - is one of the most ludicrous moments in the series (close to Elayne's notion of romance: You slept with those two, so it's my turn now.)

-The "hanging city" that Rand and Asmodean saw as they chased the Shaido into Randland.
As a potential source of tools and information, Rand really should've checked this out by now. He could've done that instead of one of the 7000 times he recited a list of brave women who died for him.

-The Dragonsworn spread awfully fast through a huge chunk of Randland. Wouldn't they have needed some kind of backing to worship a widely-hated figure? It seems that they would've been crushed long beforehand by local authorities, and this probably provides the best clue to Demandred.
Sammael's famous "events to the South" line certainly drew attention to this. Their actions seem straight off the list of Forsaken atrocities: extortion, rape, mass killings, child murder, mob behavior, toppled rulers, and resulting complications for many of the groups throughout Randland. I despise everything about this group, including how much time they drained out of the novels, so I won't elaborate. It's just possible that Sanderson was throwing us a bone reemandred.

-Mazrim Taim had Gedwyn search for something after rescuing Rand from the WT Embassy. Mazrim and Gedwyn share a look, then Gedwyn shakes his head. Mazrim then frowns.
What was that about? Was Gedwyn looking for the little fat man angreal of Rand's? Dumai's Wells is the key point after which it can't be found. If he was, and didn't find it, then who does have it? Dashiva is introduced in the same chapter, so I suppose he would make the most sense. However, if it was Dashiva, that would probably create the least impact on the coming books.

-Herid Fel's murder. One of the Shadow's most elite assassins - power-proof, no less - is sent to kill an old man. Ishy/Moridin was a philosopher, and it seems that philosophy itself lead him to follow the Dark ("reason" drove him mad).
How is pure philosophy so dangerous or powerful? And how did they know to kill Herid Fel? He signed off on Rand's plan for The Cleansing, but the Forsaken (collectively) didn't know about this plan until Rand was going to carry it out. If the Shadow knew about Fel's advice on the Seals or the Last Battle, how did they miss The Cleansing?

-Lews Therin was non-existent until TSR. By LoC, Rand is sharing guacamole recipes with the disembodied guy.
Is LTT Rand's manifestation of madness? If he's really connected to Rand like that, does it count as madness in the WoT? If LTT's voice isn't the way in which Rand is mad, then what is? Why did LTT only come out after TDR? Was it Rand's use of Callandor?