We know that many, many people are tired of "crunch." What would be recommended as good "fluff" products? Other than Silver Marches, of course. (I love that book . . . very well done!)
For me, two books which have great and useful "fluff" are Manual of the Planes and Faith & Pantheons. Technically they're not probably fluff books but the rules-free descriptions of planes in MotP and of deities in F&P are great, respectively for the DM and the players. While the deities stats in F&P are utterly useless, the rest it's still a good source for our character ideas.
Manual of the Planes and Monte Cooks Beyond Endless Doorways. Both are excellent, very imaginative, but if you aren't much into other planes they might lose some value. Great for mining ideas in any case.
Book of the Righteous is probably one of my all time favorite books for the way it reads. Very imaginative and full of ideas with a complete pantheon and religion that makes sense for a fantasy campaign.