"The DADA Professor" by RJLupinFan

I don't really know what to say about this fic.

http://www.fanfiction.net/s/4088288/1/The_DADA_Professor

It's about a seventh year student who gets a crush on Lupin while he's teaching at Hogwarts. It's bit hackneyed in some respects, and the writing's rough, but it's charming. It's not about a Mary Sue gushing about a Professor, it's as canon as one of these fics can be, minus one eye-rolling, backbended way of getting Lupin and the student to kiss.

I don't know. There's something to this fic. It's worth reading.

The "Alexandra Quick Series" by Inverarity

A series about an American witch at an American wizarding institution.

http://www.fanfiction.net/s/3964606/1/Alexandra_Quick_and_the_Thorn_Circle

http://www.fanfiction.net/s/4684861/1/Alexandra_Quick_and_the_Lands_Below

http://www.fanfiction.net/s/5784632/1/Alexandra_Quick_and_the_Deathly_Regiment

One of the few things Rowling got right in the last books was that she didn't address the Veil, (and I commend her for that because in every other regard she threw subtlety out the window,) but Inverarity discusses the Veil head-on, and comes out with a pretty good story.

I love this series. It's especially amusing if you know anything at all about American history.

I believe it's Inverarity's plan to write seven books (admirable, really), and the series is much more tightly-connected than the HP books, I would say. Book three feels like the second half of book two, for example.If I had to make any complaints, it would be that I miss some of the canon characters we know and love. There are references to canon sprinkled throughout, but it's not quite the same, you know?

And also, I'm just stating for the record that any coincidences between this series and the (non-fan)fiction series I'm working on are purely that. We even use similar names. Maybe that's why I like this series so much. Sheer narcissism.

"My Immortal" by XXXbloodyrists666XXX

I don't really need to talk about this story, I just wanted to post it because I genuinely love it. If I had to name my favorite fanfic, this would probably be it.

http://myimmortalrehost.webs.com/chapters122.htm 

"Harry Potter and the Slytherin Spy" by Christine Morgan

What if there was another Hogwarts student in Little Whinging?

This fic, written/set right after Order of the Phoenix, is about Harry meeting a Slytherin girl and forming a friendship with her in his sixth year. It's fairly-straightforward and not excessively (wonderfully) violent at all. (Sarcasm.)

http://www.eskimo.com/~vecna/hp_spy_01.html

Morgan can imitate Rowling's writing style well, and there is something so satisfying about reading a fic you can confuse for the genuine article; especially when it gets to where Morgan is describing gruesome deaths in Rowling's simple, yet descriptive prose.

I'm not pretending this fic is without problems; it's focused on a female OC, which is a no-no to most in the fandom, though trust me when I say the writing is good enough you won't care. And there are a few canon things that would raise eyebrows - Kreacher's characterisation is all wrong in this fic, in my opinion, while I think Morgan's explanation of where Sirius was hiding during Harry's thirteenth summer is a brilliant twist. Morgan also abuses ellipses, and the ending seems a bit rushed and simplistic, but trust me when I say:
YOU SHOULD READ THIS.