In Burn Notice, there is a character who works for a rich man and is framed for a crime. He's the same actor as Batista in Dexter.
In Chuck, Harry Tang is played by CS Lee, who plays Masuoka in Dexter (I kept wanting Tang to do Masuoka's dumb laugh).
In The Mentalist episode 6, the wife of the victim is played by Andrea Parker, who plays Miss Parker in the Pretender (and a sexy secretary in Brisco County, Jr.)
Neil Patrick Harris was in an episode of Numb3rs (man, kouaidou, now I'm reading it as "numbthreers" too), and I've been told several times that my brother looks like him. I agree, but only at a quick glance.
Russ Brennan from Bones is also Paul Steven, an arson investigator in Numb3rs season 2.
You know, most of the time, I don't have time with actors in movies, but for some reason if an actor plays distinctly different characters on tv shows, it feels... weird. =\
P.S. Dr. Lightman in Lie to Me angers me so much. STOP READING EVERYONE. I would be like, "YOU WANT TO SEE WHAT ANGER LOOKS LIKE? NYAAARRGHHHH!!! *punch punch punch*" ....except it would be more like, *flail flail flail* and he would be like, "And that's frustration." And the whole situation would be a downward spiral for me. Bottomline of it would remain the same. He pisses me off. ...but not enough to make me stop watching the show... I mean, I'm only two eps in.
Edit: HOLY CRAP CAM, why are you in Numb3rs? This is so crazy. Sure, it's not actually Cam, but the character she's playing seems to be just as badass. =3