As you can see from the widget on the side of this blog, I don't mind Shelfari. It's a good way to track which books you've read and since I'm aiming for 50 on the year, I need all the help I can get. Shelfari right now is the best of the worst.
What I really want is to find the imdb of books. While Shelfari obviously can't compete in terms of scale--in large part because people generally watch tons more movies than they read books--they can compete with their interface.
The one particular suggestion I have to make is that they change their voting system from 5 stars to 10 stars. 5 stars makes no sense, because people are extremely unlikely to give a book 1 or 2 stars, and every rating oscillates somewhere around 4.
The most annoying part is that imdb has proven how successful a 10 star system can be. Their top 250 is unrivaled, and there's no way it could exist with a 5 star voting system. Plus, it's not like 10 stars is any harder from the voter's side, as you're still just clicking on one button.
I'm sure that Shelfari has some employee that scans the internet looking for sites that mention them. If you are that employee, and I still have your attention, please forward this to your boss (or maybe you are the boss). Either e-mail me one good reason that it wouldn't work, or let's make this happen.