Very true. I remember reading that story whan it was posted as one chapter, not sure where it was. But the Human/Dragon Slash combo definetely made it very interesting. I liked that and the fact that the story avoided seme/uke cliches. It was something different and fresh. 
Overall, I like stories where fantasy world bleeds into reality, be it Demons, Vampires, Aliens, Elves, you name it. Harry Potter is like that  
I like mixed pairings like: 
 Wizard/Human, 
 Human/Demon, 
 Demon/Elf and so on 
Let's not forget Were-whatever beasts! There is a Slash fic in the Horror/Thriller section where this school teacher gets bitten by a werewolf and is slowly changing. Pretty deep descriptions of how it went and the story will most likely end up as Human/Werewolf pairing.