- 24 (season 6).
- 30 Rock (the second half of season 1 and all of season 2).
- Battlestar Galactica (the second half of season 3).
- Big Love (season 2).
- Breaking Bad (season 1).
- Chuck (season 1).
- Curb Your Enthusiasm (season 6).
- Damages (season 1).
- Dexter (season 2).
- Entourage (season 4).
- Friday Night Lights (the second half of season 1 and all of season 2).
- Gilmore Girls (the second half of season 7, its final season).
- Heroes (the second half of season 1 and all of season 2).
- It's Always Sunny in Philadelphia (season 3).
- Lost (the second half of season 3 and all of season 4).
- Mad Men (season 1).
- The Office (the second half of season 3 and all of season 4).
- Scrubs (the second half of season 6 and all of season 7).
- The Shield (season 6).
- The Sopranos (the second half of season 6, its final season).
- Veronica Mars (the second half of season 3, its final season).
- Weeds (season 3).
- The Wire (season 4).
- - - - - - -
A subsequent question is whether the Golden Age is over. I don't think it is, but maybe we could map it like this:
- 1999 - G.A. inaugurated (The Sopranos, The West Wing, Freaks and Geeks, Buffy the Vampire Slayer, Sex and the City, X-Files, Friends, etc.)
- 2001-2006 - G.A. ramping up (The Shield, 24, Arrested Development, Office, Lost, Battlestar, Friday Night Lights, Deadwood, above shows continuing)
- 2007-2008 - G.A. apex (shows listed/overlapping in timeline)
- 2008-2012 - G.A. epoch (Parks and Recreation, Community, Justified, Game of Thrones, Walking Dead, Modern Family, Happy Endings, Homeland, New Girl, Treme, Boss, Boardwalk Empire, etc.)
- 20?? - G.A. declines (at some point it must, right?)
A final point worth noting is that the latter third of this timeline (i.e., the spring of 2008) coincides with the writer's strike. Looking at the list, however, what's interesting, and possibly surprising, is how few of the top tier shows were affected.
First of all, the non-network shows were fine (AMC, HBO, FX, Showtime, SyFy), either running prior to the strike or airing an already-finished season during the strike. (Breaking Bad, whose first season did end up getting cut short, has obviously turned out just fine.)
As well, Lost was mostly unaffected because they wrote and filmed much of the fourth season in advance to show in the spring of 2008, as part of their 3-season, 16-episodes-each deal. From memory, it was primarily The Office, 30 Rock, and Friday Night Lights that suffered -- each effectively ending its season prematurely, in the middle of storylines. For the first two, though, the previous spring and fall (of 2007) were creative peaks -- the former declining thereon, the latter largely sustaining its quality. Friday Night Lights, on the other hand, did unfortunately have its series low point in season 2, even as it retained its quality outside of the goofy and foolish murder storyline.
Some pop culture food for thought.