We do look at the book vote results when commissioning book titles - and at every 'hit list' meeting (which Richard has blogged about in the past) we go through the titles that have performed well in the book votes. In fact, over the next couple of years there are a few titles that have featured in our book votes which will actually be published - exactly which books I am not allowed to reveal just yet, but keep an eye on the blog and I will reveal them as soon as I am allowed to.
Unfortunately, actually getting an archive for these book votes up and running has proved more complicated than we had expected - so we have been unable to come up with an automated system to display the results. We are still working on this, but as a stop gap we have created an article page which I will update on a monthly basis which will show you the book vote results.
Here is the Book Vote Archive.