Carl sent me a link to Terry Windling's wonderful essay on Rapunzel. Although a long-time fan of Endicott Redux and Windling's art and essays, I had not read the essay which gave a recounting of the tale's history and transformations, some psychological insights into the story, and an excellent list for further reading.
She gives a positive review of Zel: "It's a taut, beautifully written novel and highly recommended." Her description of Touk's House by Robin McKinley is intriguing, a re-worked version of the Rapunzel tale that definitely sounds worth a read.
Carl also included a link to some of Windling's other articles and if you are reading fairy tales as part of the Once Upon a Time Challenge, you may find an essay on your character or tale.
Another of my favorite sites is SurLaLune fairytales. com. Where you can get tee shirts, book bags, etc. with images by the most famous illustrators of fairy tales. Check out the tote bags here. SurLaLune also gives annotated versions of many tales and also their history, modern interpretations, similar stories across cultures, etc.