Riding Shotgun by bythedamned.
http://bythedamned.livejournal.com/10729.html

College Bound by Neonchica
http://neonchica.livejournal.com/8450.html

We Mortals Be by Debbiel66
http://debbiel66.livejournal.com/10418.html

On a Wing and a Prayer by Sinestrated (wincest implied, but i consider this as gencest, tbh)
http://sinestrated.livejournal.com/44354.html

Raising a Big Brother 'Verse by Authoressnebula
http://authoressnebula.livejournal.com/601881.html

My Life's Come Off It's Tracks by Mimblexwimble
http://mimblexwimble.dreamwidth.org/81268.html

Ten Thousand Miles by Mimblexwimble
http://mimblexwimble.livejournal.com/54645.html

Strangers and Angels 'Verse by Reading
http://reading1066.livejournal.com/tag/strangers%20and%20angels%20universe
http://www.fanfiction.net/s/2748108/1/Strangers_and_Angels

When It's Over by P.L Wynter. It has Sam/OFC but the Dean+Sam bromance aspect of the story is a prominent one.
Fic Warning/Spoiler: (highlight to read): ****
http://www.fanfiction.net/s/2865835/1/