Tim Waggoner talks about the biz of tie-in writing over at Writers Digest.

Christopher Golden, bestselling author of The Ferryman and Strangewood, has written "Buffy the Vampire Slayer"-related books, and novels based on the "Angel" TV series. He’s witnessed first-hand the problems some writers—even good ones—have constructing a story within someone else’s guidelines. "I’ve also seen a lot of god-awful tie-ins," he says, "which would seem to indicate that some writers think it’s a lot easier than it actually is."

Slate wonders if novelizations are endangered species:

novelizations have been supplanted by big-selling tie-ins—original novels based on existing properties such as Buffy the Vampire Slayer, CSI, or Halo—and the Internet. In a DVD world, the idea of using a book to relive the pleasures of a film is practically counterintuitive.

[…]The home-theater revolution may have wiped out a large part of the novelization market, but the lessons learned may wind up sustaining the genre. When DVDs first arrived, the studios quickly realized that they could get fans to "double dip" by issuing a bare-bones release of a movie and then following it with a "Deluxe Edition" loaded with special features. Now it looks like literary special features—expanded back stories, cut scenes, and deleted characters—might just make the novelization relevant again.