or … “Well what did you expect in an opera? A happy ending?”
I just watched this 5 minutes ago. On Numbers, some of the characters sit down to watch TV, and we hear the theme to Taxi. One of the actors is Judd Hirsch, who was on Taxi.
There was an early episode of BattleStar Galactica where the actor who played Captain Apollo in the original series now plays a terrorist leader who has taken control of a prison ship. Captain Lee Adama (Apollo’s analogue in the new series) ends up in a fairly long conversation with this fellow, mostly in a political debate, IIRC.
I haven’t read past page one of this thread yet, so I’m sure someone else has mentioned this “Boston Legal” self-reference: In one show, Denny Crane has been conspicuously absent for most of it. Near the end, Alan Shore bumps into Crane in the hallway, and says, “Haven’t seen you much in this episode.”
Richard Hatch (the actor who played “Apollo” in the original show) is a recurring and fairly important character in the new series.
Let me try that again. Richard Hatch plays a recurring and important…, etc.
How about Spaceballs, where they watch the video to find out what happens next.
RealityChuck mentioned it in post #93.
He must have fast-forwarded past that one. 
Friday’s episode of Numb3ers had sort of a meta-moment. At the end of the episode, Judd Hirsch, who plays the father of the math genius and the FBI agent, gets his sons to sit with him and watch some TV. One son starts flipping around with the remote, and settles on a channel. As the Numb3rs credits begin to roll, the theme from ‘Taxi’ is heard from their television.
Sorry, Pigs in Space. I see you already got that one.
In one episode of Monk, Capt. Stottlemeyer announces to Adrian that the Police Department has signed a new contract with Monk “guaranteeing him 13 cases a year for the next three years”, a reference to the network picking up the show.
The Nanny also had a guest appearance by Stephen Nichols playing soap star Brock Storm. He took Fran out, got nasty in the car, and when Fran protested such behavior coming from a guy who plays such a virtuous character, he said “I’m not Dr. Storm. I’m his evil twin” and put on an eye patch.
Steve Nichols played Steven “Patch” Johnson on Days of our Lives for years opposite The Nanny’s Charles Shannessy, who played Shane Donovan.
Monk has had several episodes with sly in-jokes referencing the stars previous roles. one episode had them meet Tim Daly on a plane, and Bitty Schram (Sharona) mentions liking his old show Wings, (which Tony Shaloub also was on), he deadpans, “I never saw it.”
On that same episode, Garry Marshall had a cameo and interacted with Bitty Schram. They were both in A League of Their Own.
Other episodes have poked fun at Silence of The Lambs, which Ted Levine (Captain Stottlemeyer) starred in. One episode had Monk chasing someone around wearing night-vision goggles, and another had them passing stuff back and forth in a basket on a rope to an enviromentalist camped out in a tree.