There are two sites you should be following avidly (one of them especially if you're based in the UK):
This is the Radio 4 Podcast website which has recordings of some of the best archive material on science and nature, as well as philosophy, politics, arts, history, ethics and mathematics. In fact, every AOK relevant to your TOK essay and presentation research. The podcasts last from anything between 15 - 45 minutes. The recent one we followed was a fascinating journey into the history of the brain...
If you've been following the toktutor tweets above, another great tweet to follow is 'TOKtweet' as it gives you up to the minute links to web articles on all aspects of TOK and is authored by no less a figure than the writer Richard Lagemaat. Superb for TOK essay and presentation research.