I like wikipedia because you find information about pretty much anything. If you are a curious person and bored you can just go to wikipedia, go to a random article and learn something new. It might not be very practical, but it might help you think of something more interesting to do. Obviously its not a place to do scientific research, but the sources on articles can often times be quite valuable and help you find a more detailed source of information. Wikipedia is a great place to read biographies about real people. It can also be used as an unbiased news site.