From "Unfriendly Chat" in Season 7: The CSI's are all trying out a Brand X version of Chatroulette and Omegle. Jo connects with a Marine stationed in Afghanistan. They chat for a little bit, and the Marine (a Southerner) tells Jo that he's never been to New York. She walks her laptop over to the window, and shows the Marine the New York skyline through the webcam.
The montage of the three canon couples at the end of 'Blood Actually'. Especially Mac and Christine's dance with Josh Groban playing piano.
The last two scenes of 'Today is Life'. First, the team has a nighttime gathering around a portable fire pit up on a rooftop, showing how they're one big family. Then, Mac goes and proposes to Christine, who accepts. (Trouble is, knowing it could be the last scene of the last ep ever brings a simultaneous Tear Jerker aspect to it as well.)
In "Yahrzeit", Mac returning the brooch to Hannah Schnitzler.
Gina Mitchum in "Silent Night" expressing her wish to help Taylor after he helped to safely disarm her kidnapper.
Cliff coming to visit Flack and inviting him over for supper.
"It Happened to Me", after Hawkes has admitted to losing everything:
Mac Taylor: I have an extra room. (Tosses Hawkes a set of keys) It's not up for discussion.
"The Untouchable": Tessa James's faith in Mac Taylor, and his insistence that what she said had a deeper meaning.
"Air Apparent": Don Flack making amends with his sister and helping her get a job.