If you love books, then OO.sg is a book heaven. They have thousands of titles you can search from or just browse through their categories of best-sellers, recommended and on sale books.
What I love about this site is that once you've searched for a title, it gathers the availability, cost, delivery time and rating from 9 popular online book stores (ie, Amazon, Book Depository, Open Trolley, Fishpond, etc) therefore giving you all the information you need to compare and make the best decision on where to buy the book.
Costs are broken down into book amount + shipping to Singapore which is really informative. If you ever need to find a book, I highly recommend OO.sg as your go-to site for books!