A Threefold Path to Redemption (http://rei-c.livejournal.com/952440.html) by rei_c: "Sam finds a way to keep Dean from going to hell: he'll go in his brother's place. He knows it's going to be bad and that he'll emerge changed. He never knew how much." (Sam/Dean; long and not for the faint of heart - heed the warnings)

Now We Are Come Into Our Kingdom (http://archiveofourown.org/works/54987/chapters/72917) by cormallen: "It's been months since Dean sold his soul, and Sam's run himself ragged trying to find a way out, Chinatown to "Amber Moon", South Dakota to Connecticut. So far he's got nothing to show for it but some cryptic words – "You've got the 'what' and the 'where' and the 'when', and you think you're missing the 'how'. You aren't, of course, only you haven't figured that out yet." There's a possessed girl following him around, Dean's trying his hardest to drive Sam insane with jealousy, and the visions that were supposed to stop when Azazel died still wake him night after night after night." (Sam/Dean; Sam is a little morally ambiguous by the end of this one, in case that's not your thing)

Regrets Trilogy (http://samdean.archive.nu/series.php?seriesid=95) by jassy: "Sam refuses to allow the Crossroads Demon to have his brother." (Sam/Dean)

Here There Be Tygers (http://kalliel.livejournal.com/206457.html) by kalliel: "The problem with Dean's memory is, it means he asks that question about eight trillion times more ("Sammy, are you okay? well, are you?") and as far as Sam's concerned, the answer matters even less. The problem with Dean's life is, it's supposed to end this year. And the problem with Dean's brother, well. Sam's still working on that one." (gen)

The Firefly that Loved Metallica (http://fleshflutter.livejournal.com/3749.html) by fleshflutter: "In which Sam has a bottle full of soul." (Sam/Dean)

The Descent of Innana (http://vaingirlfic.livejournal.com/32303.html) by vaingirlfic: "Sam gets Dean out of his deal by making a worse one." (Sam/Dean)

There's also a bunch recced here (http://spnstoryfinders.livejournal.com/9820056.html).