NOTICE: Unfortunately, maintaining these recs pages has gotten to be too much work, given the amount of fic that I read. So from now on, I'll be keeping track of good fics via my AO3 bookmarks and the delicious account Grey Bard started for me.
I'm not really in the Sentinel fandom (my father's name is Jim, which is a permanent stumbling block), but people recommended lots of good Sentinelfic to me.
What Sentinels And Gay Men Have In Common by Annabelle Leigh
Diamonds and Marinera Sauce
Wine, Women and Schlong
Fruit of the Vine