I can be a beta for stories that have an original plot, (meaning non-canon). It's not that I don't like canon but canon has way to many holes... Ginny Harry = not happening in my mind, although there have been a few well written fics that have the pairing, but they are few and far between.
Dumbledore to me is flawed, not evil, just old and almost senile... The Weasley's and as a ginger myself I hate to say it was all a manipulation to begin with... we have Molly screaming platform 9 3/4 when she's had multiple kids go through the barrier and all of a sudden she doesn't know where it is... JK as much as I admire books 1-4 you screwed your own pooch there...
I've read almost all HP fanfic that has been worthwhile, and as much as I'd love to write myself my ideas escape me before I have time to jot down notes about those ideas... I have dozens of drafts of stories I'd love to be done, but I know I could never do them justice.
If you'd like a beta for a non Ginny/Harry story and would like to test me send a very rough draft of the concept my way and let's see what happens. :)