TED is possibly one of the best resources for a student to use. You learn important information through fun and entertaining presentations and they are very good to use if you yourself are doing a presentation (especially great to waste a bit of time!)
TED stands for Technology, Entertainment, and Design and tries to focus mostly on the entertainment side because that is what started the company. It started with a one of convention in 1984 but then in 1990 it became a regular thing due to popular demand.
I think that one of the reasons why TED is so successful is that it covers a wide variety of topics and famous guest speakers. Personally, my favourite presentations are about film and TV (presented by big directors like JJ Abrams James Cameron) and also scientific presentations, specifically about evolution and the history of the universe.
As TED became more and more popular, it attracts big keynote speakers. In the past there have been talks by politicians (Bill Clinton, Gordon Brown), scientists (Richard Dawkins) and millionaires (Bill Gates). Whenever I have a presentation, the first thing I do is go to TED to try and find some inspiration.