Here is a prototype of a library catalog (III's Millenium) wrapped on the library website with Drupal (a MOSTLY opensource website content management system -- mostly because a commercial version of Drupal is now under development).
The Drupal module for integrating the library catalog includes modules like ratings (Fivestar), Faceted Search, and Similar by Terms.
Drupal is built with modules which can work together (like legos, sort of). I've been working with Drupal for my portfolio site located here. I'm going to give this module a try to see if I can get it to play with Voyager/Ex-libris. It seems like a possibility as it works with the MARC records, but I don't know how much configuration it will take or whether it will even work... but I need to get to work on my drupal site, so maybe this will provide an incentive. ;-)
I thought it was an interesting project, although I'm not so crazy about the color scheme.