4 and/or 5
Blind Sam. I LOVED it. :-)
Second Sight http://assignations.org/spn/sight_index.html

Brain damage. This one is very bittersweet; I cried bucket loads!
A Life Redirected http://www.fanfiction.net/s/3533659/1/

4.
J2 slash
I Drew A New Face and I Laughed This is f-locked
http://ilikecrystals.livejournal.com/23377.html?#cutid1

gen, Sam and Dean
A Little More Tequila, A Little Less Demon Hunting http://www.fanfiction.net/s/3110914/1/
What if Sam and Dean had had Max's childhood? Inspired by what would have happened if John had taken the "little more tequila, little less demon hunting" route. Title borrowed from Sam's line in "Nightmare." AU except for obvious necessary details pulled from the first scene of the pilot. Lots of mini Sam and Dean in the form of flashbacks.

Gen
True Brotherhood http://www.fanfiction.net/s/4688315/1/True_Brotherhood
and the sequel Brotherhood's Bond http://www.fanfiction.net/s/4859139/1/

Gen
Safe In the Arms of Love http://www.fanfiction.net/s/4190672/1/ Summary: Total AU Dean Winchester was just your average joe working as a mechanic in his hometown of Lawarance,KS when he met Sam Logan and everything changed.
sequels Into the Real World http://www.fanfiction.net/s/4398290/1/
and Family Matters (which is still being written) http://www.fanfiction.net/s/5679532/1/

AU version of how they defeat Lucifer, but it isn't really AU otherwise.
The Wall http://www.fanfiction.net/s/5979923/1/