Readers' Advisory

Have you checked out Goodreads? It's pretty popular, and I think it does roughly what you're suggesting.

How will your service be different?

Library Thing was what I used before I switched to GoodReads. You might check both of those sites.

Edit to add: I make that suggestion because the "connection" sites and tools work best when they know what a reader has already enjoyed. I forget where I read it, possibly Making Light, but I remember seeing an editor say that the best predictor of whether or not a reader will enjoy a book is if it was written by an author they already know.

It's true, at least for me. There are a crapload of generic fantasy and sci-fi books on my shelves, proving that I am not all that picky. And yet I've turned up my nose at dozens if not hundreds of virtually identical books because I didn't already know the author. A new author has to do something pretty different to break through my indifference.

So these tools have to:

A) Know what I have already consumed
B) Know what I like
C) Know what it is about the things I like that might be similar to other books

A recommendation has to come from either a pretty sophisticated algorithm, or from a friend.

Obviously, there's no need for help or advice when reading books by writers I already know and love. For new writers, I read from the bestseller list, and from what my friends say are good books by new writers. Other than this, pretty much every library has a new book section, and it doesn't take long at all to go through it.

I never, ever get a book from a new writer because of a review, which is all a reader advisory really is. I've been burned far too many times this way.

Honestly, finding good genre books is already too easy, which is why I have about ten years worth of reading in my TBR stacks.

I think GoodReads and the like have beat you to it, but, hey. Study them to see if you can't find your own twist and offer something unique.

GoodReads, like Netflix, seems to work by asking the reader to rate already consumed product (books/films) in their genres of interest. They then suggest supposedly similar books and films. Already read these? Rate them -- more suggestions will pop up. The idea is that the more product you rate, the better the service will get at pitching back stuff you'll like.

Myself, I mostly find new books by browsing reviews, Publishers Weekly, and my BOMC catalog.

Shelfari does this, too, I believe.