There's not much I can say that we don't know or can infer from canon, of course, so I'll stick to the specifics of how I'd like to play her:
* She isn't dating Harry, and doesn't plan on running into his arms any time soon. Firstly because she's got other things on her mind - like Fred - and secondly because she doesn't want him to take her for granted. He'll have to work to get her!
* She's still really upset about Fred's death, though instead of becoming overtly angry - her anger and frustration is sort of seething and bubbling below the surface mostly - she's rather quiet and withdrawn. It'll take her a little while to get back entirely to the fun loving, boisterous sort that we all know and love.
* Quidditch is totally her main way of venting, right now, so watch out or you might get a Quaffle to the head! She isn't helping out at school because her mum's keeping her at home for safety, and she's a little scared of going back anyway.
* She's torn about what to make of the trials. For the most part, she thinks those who get punishments totally deserve what they get (and more besides - if you were one of the bad ones last year, watch out!), but Hermione's a calming influence and Ginny's just sick of all the fighting. Ugh.
* You'll encounter her if you're taking NEWT COMC, Charms, DADA or Transfiguration, and of course the Muggle Studies class. Asides from Quidditch, she's also in the Slug Club, though she's a bit "meh" about that now.
PLOT WITH ME!
And also, on Nigel's behalf, does anyone want to log? Roland's on his third currently and he's feeling left out. :)