The best thing that I am benefited through Internet is the search engine. For eg. If you have any doubt about any thing, you can easily clarify that by using the major search engines like Google and Yahoo. Whether you want to see a horse with horn or the world biggest dogs or cats or need to download your favorite music or video, the Google can help you.
Secondly I can use email, video chatting and social sites like Facebook. Many free services of Google such as Gmail, Google Maps, Google Bookmarks, Youtube, Google Books might be useful for those who love Internet.
To my knowledge many people are earning great money through programs like Google Adsense and other affiliate programs.