OoP Spoilers - Hints left hanging

[lhunneb]

No: HPFGUIDX 63117

I've just started re-reading the book, specifically looking for hints 
or bits of information that JKR have been included in the book but 
not brought to any conclusions in OoP.  They might well be fodder for 
the next two installments.  

These are just a few loose ends I've noticed so far.  Who else has 
some:

1) List of Sirius' family.  There was a lot of information provided, 
much of which wasn't followed through very extensively.  Lots of 
source material here.

2) Photo of original Order of the Phoenix.  Like the Black family 
tree, lots of potential for expanding these stories.

3) Aberforth Dumbledore.  I can't believe that JKR would tell us that 
Albus has a brother without him coming into the story somewhere.

4) Luna Lovegood.  While we've already learned a little bit about 
her, I think she is going to become pivotal as we go forward.  What a 
wonderfully weird and mysterious character!!

5) Percy Weasley.  We haven't seen him come up to the final crunch 
here.  How will he come into play?  I must say that several 
possibilities come to mind...

6) Viktor Krum.  Hermione has been corresponding with him, keeping 
him in the story.  That has to be for a reason, don't you think?

7) Harry's DADA class.  I think that the list of students who chose 
to participate will become important.  Will they become the junior 
Order of the Phoenix?

8) "Power the Dark Lord hath not."  I know that Dumbledore has 
essentially explained that this power is Harry's heart - his love.  
But just knowing what it is can't be the end of it.  I think this 
will set the fundamental underpinning of the last two books.

Those are just the first ones that I came up with at a glance.  What 
else do you see?