Lakshmi Pratury remembers the lost art of letter-writing and shares a series of notes her father wrote to her before he died. Her short but heartfelt talk may inspire you to set pen to paper, too.

Lakshmi Pratury is the Co-Host of TEDIndia 2009 and founder of Ixoraa Media, whose mission is to strengthen the ties between United States and India through sponsored corporate, cultural, and… Full bio and more links

Nandan Nilekani, the visionary co-founder of outsourcing pioneer Infosys, explains four brands of ideas that will determine whether India can continue its recent breakneck progress.

Nandan Nilekani is the author of “Imagining India,” a radical re-thinking of one of the world’s great economies. The co-founder of Infosys, he helped move India into the age of IT. Full bio and more links

Anand Agarawala presents BumpTop, a user interface that takes the usual desktop metaphor to a glorious, 3-D extreme, transforming file navigation into a freewheeling playground of crumpled documents and clipping-covered “walls.”

Anand Agarawala is the creator of BumpTop, an irresistible new desktop interface with a satisfyingly three-dimensional physicality and a fresh approach to interactivity. Full bio and more links

Seth Godin argues the Internet has ended mass marketing and revived a human social unit from the distant past: tribes. Founded on shared ideas and values, tribes give ordinary people the power to lead and make big change. He urges us to do so.

Jimmy Wales recalls how he assembled “a ragtag band of volunteers,” gave them tools for collaborating and created Wikipedia, the self-organizing, self-correcting, never-finished online encyclopedia.