You've got a lot of great recs already (I guess you'll be occupied for a while), so I thought I'd list a few communities relevant to your interests that you might want to check out once you feel like going on a treasure hunt by yourself:

spn_gen for a rather steady supply of gen fics
spngenlove for themed gen recs
spn_epific for episode tags and codas
bystanderfic and spn_outsidepov for outsider POVs
copsandhunters for "The Lawmen (and Women) of Supernatural"
sam_castiel and deancastiel are mainly for the pairings, but there are a good deal of gen fics there too.
spnmysteryyears for Stanford-era fics
spn_women for the female influence.

Don't be scared, not all of them are terribly active.
(and I'm so going to bookmark this thread...)