I was having my semester exams for the last 2 weeks and as most of the guys, i study last minute.
2 Days away from exams i discovered that my text books recommended by teachers are rubbish and i need a quick solution. Then,i found this really neat website that had a lot of the books i needed, helped me a bit.

The website is : Gigapedia

I have just used it for reference books till now, don't know about other type of books.
I recommend that you have a look at the book and if you like it, please go buy it. I do not want to promote downloading of such content, but here you can pick what you are comfortable with and decide if you want to buy it or not.

If you know of any similar websites, do feel free to post the link in this thread, i would stick to reference books and not other type.