How about something that follows that line of thinking, but able to be taken both ways.

Examples:
If you like Brian Jacques's Redwall series then you'll love Roald Dahl's children books.
-or-
If I really like Ursula K. LeGuin's Earthsea series, then who/what should I read next?

I think having the ability to ask for a recommendation based on what someone has previous favorites would be really useful. Especially when a community can throw their best guesses at what this someone would like

Not a bad idea and something that could fit easily within the current recommendation forums!

Fab idea that. You could use the subject header for eg.

IYLYL — IYL Stephenie Meyer YL Rachel Caine's Morganville Vampire series.

Just like bookshops do here in the UK. The IYLYL stands out and always catches my interest. I think this would prompt a lot of interesting posts.

Oops .. forgot to put:

IYLYL = If you like you'll love ...

Except avoiding the obvious. I worked at a Borders (a giant book chain) here in the US for over a year and they loved to make obvious If You Like [x] Then You'll Love [y]s. If you liked the Illiad then you'll love the Odyssey. Or if you liked Kite Runner then you'll love Thousand Splendid Suns or Kite Runner in Large Print. (Both true stories, it was embarrassing for me to even put the displays up).

Hi oldrobotsnerrust,

I like your idea too.

Will come back to this topic at the weekend when I'm back home from my business trip to Finland.

Huh, wow. I guess I really live in a backwater place; none of our bookstores do that kind of thing (yet).

There are an awful lot of L's and j's in your hometown. Not that there's anything wrong with that

I guess that's true, never really thought of that.