What were the biggest hidden clues in OoP ?

[Miller, Gina (JIS)]

No: HPFGUIDX 96043

Kristen wrote:
> Just curious what you all think are the biggest hidden clues in 
> book 5. This means information that JKR mentioned in passing that 
> will become important later in the series.

Reply by Gina:
I was looking at the Delores Jane Umbridge - Hermione Jane Granger 
connection last night and you can get Dumbledore out of the analogy 
and you can get Hermes. People have mentioned Dumbledore being animigus 
could he be Hermes? Or does this spell something else? You can also get 
Order is in Danger, but with words  left over...any ideas? 

Gina