Literary Spin-Offs: Yay or Nay?

I loved Wicked and the other Gregory Maguire spin-offs. So when FlavorWire did a Required Reading post on the 10 Great Literary Spin-Offs I was interested to see my other options. They even mentioned a book I recently read (and thought was great) called March that is a spin-off to Little Women. And while they weren't all my first choice to see spin-offs of (I HATED Beowulf and can't imagine reading a spin-off) they had some good recommendations.

I have heard of Wide Sargasso Sea before - but haven't read it. The Hours was a great book (and movie) and I'd love to reread it. I've never heard of Rosencrantz and Guildenstern are Dead but I love FlavorWire's description so I added it to my Goodreads wishlist.

Anyways, check out the list. But note my disappointment that Wicked didn't make it.

Any other spin-offs you'd recommend?