Patriots QB Tom Brady made a surprise appearance this week at On Cue, an annual gathering sponsored by the Boston-based venture capital firm Cue Ball. Held this year at the Boston Center for the Arts, On Cue convenes entrepreneurs, scientists, artists, and assorted other original thinkers for a series of discussions and inspirational talks. Brady was there with Alex Guerrero, the controversial cofounder of the TB12 Sports Therapy Center, and the pair talked about how Brady’s training method emphasizes muscle pliability. (They called it the “third leg” of conditioning, a complement to traditional strength and cardio training.) This year’s On Cue also honored Nicholas Negroponte, cofounder of the MIT Media Lab, who spoke with the current director, Joi Ito. Other participants included folks from Facebook, author Ben Mezrich, former “Tonight Show” band leader Kevin Eubanks, TED superstar Amy Cuddy, and faculty from MIT and Harvard.