Terry McDermott's reaction every time he's surprised by a visit from his family. It's happened three times as of the season 3 final performances - his wife and son, his aunt and uncle, and his dad - and he's been excited to the point of speechless each time.
The tribute to the Sandy Hook victims. In the wake of the tragic elementary school shooting in Newtown, Connecticut, all of the show's singers sang a candlelight version of "Hallelujah" while holding cards with the names and ages of the victims. Simply lovely.
Whenever a contestant doesn't get in, and the the one of the coaches (usually Adam) gives them a hug.
Australian auditioner Rachel Leahcar turned in a a triumphant rendition of the Edith Pilaf classic "La Vie En Rose" that not only convinced all four judges to turn around, but earned her a standing ovation from both the entire audience and the coaches themselves. During the performance, coach Joel Madden can be heard saying "Oh my God, look... people are crying!" But what really warms up the heart and brings out the tears is what happened immediately after. Visibly nervous almost to the point of terror, Leahcar tremulously admits in a desperately eager voice that she has no idea whether or not any of the coaches turned around for her, because she's blind. The judges swiftly let her know that all four turned, and about the reaction of the audience.
Another Australian auditioner, Rebecca Davis, worked through a nerve-wracking, quavering, and badly pitchy version of Coach Delta Goodrem's song, "Not Me Not I". None of the coaches turned around, but in the "after-briefing" when the coaches discussed what happened, Delta pulled the crying, obviously terrorized Davis into her coach's chair, and the other three coaches circled around close to talk to her in a much more supportive and intimate manner than they usually do. And then Delta Goodrem and Rebecca Davis duetted on the song, and it was splendid.