Harry and Ginny sculpting with different coloured fire.
Hermione and Moony's reunion.
Moony: My Kitten. My own little Kitten, for all the world to see...
Hermione: Daddy - [cue sobbing]
Many, in general, from finding out that Draco wasn't actually dead, to Neville's true reunion with his parents.
The way Harry confesses his feelings for Ginny in book five is really heartwarming. Also funny.
The entirety of Blaise and Colleen's romance. It's just adorable.
Colleen and the Pride sticking up for the Slytherins, because they hardly ever get that kind of love in canon.
Harry and Ginny's wedding night. Complete with visit from three ghosts: George, James and Lily, all of whom wish them to be happy.
Draco and Luna returning to the Pack, five months after Draco faked his death.
Remus and Danger are alive!
During the final battle, as Harry starts the process of a Heroic Sacrifice to defeat Voldemort, the spirit of his future daughter with Ginny notices that Ginny is sad about the tie between her and Harry being pulled away. She doesn't want Ginny sad so she latches onto said tie and yanks Harry back into life. Also qualifies as a Crowning Moment of Awesome.
Marcus returns from the dead.
Nadia, Remus' and Danger's daughter, is born on July 31st.
The first full moon after the above happens, Remus manages to break the curse of the werewolf.
For the first time in thirty-five years, Remus John Lupin stood human in the full moon's brilliant light.
In the epilogue, the Defense professor teaching about werewolves and how they're cured is referred to as "Professor Snape". It turns out that she is Remus and Danger's younger daughter meaning that the old animosity between Snape and the Marauders is dead and buried.