Here is a list which was published on TED Blog in August 2012. The most watched TED talks ever are...
Jill Bolte Taylor (Stroke of insight)
Pranav Mistry (potential of sixth sense)
David Gallo (underwater astonishments)
Pattie Maes & Pranav Mistry (sixth sense demo)
Tony Robbins (Why we do what we do)
Brene Brown (Power of vulnerability)
The ones with the ** are my recommendations. If you cannot watch them all, watch these four atleast. I have added hyper links to these for your convenience.