There is really only one writer who can make me visit ff.net and enjoy the experience - Ada Kensington. I read her 'What Would You See?' series of linked oneshots a while ago, and she's been on my author alert ever since.
Birch Wood and Dragon Heartstring This is her latest offering (still a WIP, I think). I'm only up to chapter two but I'm already hooked. Her 11 year old Snape, her Dumbledore, and the relationship between Tobias and Severus are all perfect. It's gen, and it's womderful. Go look.