Have been busy lately with work, watched yesterday some new talks at Africa 2007 and others given at TED and i am always amazed by the wealth of knowledge out there, which we don't know of.
Here are some interesting ones:
George Ayittey: Cheetahs vs. Hippos for Africa's future
William Kamkwamba: How I built my family a windmill
Allison Hunt: How I got my new hip
More on TED.com