I recently learnt that National Library has a “Digital Media Collection“, where you can borrow e-books and audio books online! You have to download Adobe Digital Edition to read the E-books though, but for some E-books, you can print the whole thing to a pdf file! (on a Mac, it’s as simple as Print>print to pdf)
It’s collection is pretty vast. You’ll send quite some time just getting past the numerals before you hit books that start with ‘A’! As with normal library books, books will expire after a certain time period.