If it is intellectual stimuli you seek, look no further!
I recently discovered the incredibly intellectually-packed audio/video section of the 2008 Aspen Festival of Ideas held in Aspen, Colorado (the festival was recently featured on Studio 360). The 2008 annual event featured speakers such as Bill Clinton, Madeleine Albright, Tobias Wolff, Thomas Friedman, Paul Hawken, Sandra Day O’Connor, and Charlie Rose among many others.
On the topic of ideas and festivals, as part of its 2008 Centenary Celebration (which includes a birthday party), the University of Alberta will be hosting its own Festival of Ideas from November 13 to 16, 2008. The Festival will feature leading thinkers including Salman Rushdie, William Alsop, Barbara Coloroso, Alta Charo, and Nelofer Pazira to name a few.
ADDITION: Make sure to take a listen to Sean Wilentz and Joseph Nye‘s fascinating takes on the Internet, the media, and the political centre.