This is of older date, but it's still one of my favorites: Jill Bolte Taylor's stroke of insight. (http://www.ted.com/talks/jill_bolte_taylor_s_powerful_stroke_of_insight.html)
The way she describes the progress and how she's at one time aware of what's is happening and on the other hand not. And what the stroke taught her afterwards.
Wow, this is a tough one... I have to echo Zeb and say I love Gilbert and Boite Taylor.
(Also a related aside: you can view every TED talk ever on this constantly updated spreadsheet, linked on the TED blog: http://bit.ly/fhg3Bz)
-Janine Benyus on biomimicry, and the duh-that's-obvious insight that we should be copying organic structures in the built environment
-Lewis Pugh on swimming the North Pole to draw attention to global warming--this guy can hold a crowd's attention with some serious mastery!
-Jonathan Harris has given at least two that I know of, and I just find him to be brilliant and a first-rate storyteller
-Steven Sagmeister's Things I Have Learned in My Life So Far
-For music I love Raoul Midon and Imogen Heap
-And this isn't technically a TED talk but they link to it: Steve Jobs on how to live before you die
Gah, answering this made me feel like I need to start watching a few on the daily...
I think I may have become a TEDhead ;)
I try to keep my favorites marked on the TED site (did you know you could do that?). Here are all my favorites saved to my profile on TED.com: http://www.ted.com/profiles/favorites/id/50264
I just hand-picked some of my all time favorites:
Elizabeth Gilbert on nurturing creativity
Jane McGonigal: Gaming can make a better world
Jill Bolte Taylor's stroke of insight
Aimee Mullins: The opportunity of adversity
I think the talk I reference most is Robert Zimmerman's A Healthy Take On Time, where he talks about how our perspective of time fundamentally influences our conception of value. And thus impacts the way we make decisions and interact with the world and others.
The talk I've watched the most, by far, is Barry Schwartz on Our Loss Of Wisdom. An intelligent approach to ethical living, and why we value the things we value.
While I have many favorites, one of them is about the interaction of experience and memory by psychologist/behavior economist Daniel Kahneman.
In the talk, he demonstrates and explains the difference between the remembering self and experiencing self. It's interesting because memories are not necessarily representative of the actual experiences. He also talks about how each type of self experiences happiness.
Hans Rosling's World Population Growth speech is absolutely captivating.
A great mix of pure mathematics brought to life in a clear and informative fashion, with simple props to bring warmth, wit and humour to the room.
There are so many - My current favorite is of Amber Case - studies how people’s interactions are changing because of technology.
By far, my favorite is from Ken Robinson about education and creativity: http://www.ted.com/talks/ken_robinson_says_schools_kill_creativity.html No slides, but that's exactly why he's captivating. And his ideas make me yearn for an education experience for my kids that doesn't yet exist.
As a big fan of sandbox games and AI, one of my recent favorite TED talks was Peter Molyneux's AI demo 'Milo' the virtual boy http://www.ted.com/speakers/peter_molyneux.html. His Milo project demonstrated the ability of programs to replicate rewarding emotional relationships with AI characters. Molyneux has been a very influential pioneer in emotionally engaging social gaming, and I suspect his research with Microsoft will soon be implemented not only in our games, but in our everyday utility apps.