The blog Like Fire at Open Letters Monthly calls attention to the very smart and very funny short essay by Anya Ulinich (whose very smart and very funny story “The Nurse and the Novelist” was published in PEN America 9). That essay is part of the Correspondences forum, which you can still contribute to yourself.
Also part of that forum: Sam Lipsyte’s letter to Barry Hannah, mentioned here previously and praised by the blog of American Short Fiction, along with the rest of the issue.
The email exchange between Jonathan Lethem and David Gates, also mentioned here before, was highlighted by the Book Bench blog run by The New Yorker and was called “absolutely wonderful” by The Rumpus.
(Update: GQ spotlighted the Lethem/Gates exchange as well.)
Finally, part of the story in the issue by Lily Hoang, “Sonata for a Ragdoll Without Eyes,” which is not available online—and which, appropriately for our Correspondences issue, is based on a letter Lily found—has been beautifully adapted for the web here, here, and here by W5RAn. (That’s the opening to the story above.)