This aggregator includes 756 academic, multi-disciplinary, peer-reviewed books from 22 publishers.
The site has basic and advanced search capacities. Books are not downloadable (at least the one that I was interested in was not), but, unlike Google Books, the entire text is accessible online. When a book that is searched for is found, the left margin of the page has links for the book in libraries and book sellers (print and, when available e-book versions).
The site also publishes a newsletter.