Classics Without All the Class discussion

I'm just getting started reading Holmes, and already I'm thinking about some of the many Holmes spin-off books/series I've seen. Laurie R. King has a series about Mary Russell and Holmes; I started The Beekeeper's Apprentice and never finished it, simply because I got distracted by something else. I also read Mrs. Hudson and the Malabar Rose and found it to be unmemorable.

I'm sure there are others. Have you read any? What do you like? Dislike? Should authors spin off new books about a classic character or is that literary heresy to you?

I'm enjoying the Tv series 'House'. It's a great reworking of the franchise, and kinda fun to try spot references to Holmes' world.

I didn't realize until reading some of these short stories that House was actually based on Holmes, but now it's so obvious! The drug addiction, the snide way he talks to people, the sneaky way of solving the problem... it's fantastic!

Michael Dibdin The Last Sherlock Holmes Story is a very good read, and finds Holmes on the trail of Jack the Ripper.