I love reading books and find new and exciting books to read, but is not an easy task. I try to read book reviews to know about a new book but they don´t always tell what you want to know. Something a lot better is to read books notes, or books quotes, or summaries so you know exactly what the book is about, and their key points.
Here is the list that sites that I like to visit when I want to find or learn about some book (mostly non-fiction):
1.) A Random Quote My personal project, inspired on the others. Great books summarized in 5 quotes (or less) so you can get the main idea fast. If your goal is to learn the insights from various books as efficiently as possible this is your site.
2.) Derek Sivers Books This is one of the best. Derek Sivers add notes on each book he reads, there are a large number of books covered. Also you can sort the books by title, newest, or best.
3.) James Clear summaries Popular Books Summarized in 3 Sentences or Less, but you can access a full detailed summary for each book.
4.) Mgp book notes This is a simple github page so is not user friendly, but the book notes are extensive and detailed. There are some good programming books.
5.) 4 minute books For each book there are 3 major lessons summarized so you can digest the key points of an entire book in 4 minutes or less. It is well organized and has high quality content.