I don't think it is possible for anyone to have missed
Steve Job's address at Stanford in 2005, but if you lived under a rock there it is.
On the other side, I enjoyed
Tim Cook's address to Auburn as well.
Randy Pausch's
final address to CMU is very good, and even better if you've seen his
Last Lecture.
Adam Savage's remarks at Sarah Lawrence are pretty good, but in my opinion his
TED talk on his obsessions is probably the most inspring 15 minutes I've ever sat through. Its just so good... I've watched it more times than I might care to admit.