Jason Alexander takes time off from his Chrysler commercials to grace “Unforgettable Moments in Television Entertainment: A Museum of Television & Radio Special” (7 p.m., NBC). The former “Seinfeld” sidekick appears with Michael Chiklis, Larry Hagman, Shelley Long, Bob Newhart, Doris Roberts, Cybill Shepherd and Donald Trump to discuss the comedies, dramas and reality series that changed television, and those shows that best reflected the nation’s mood or merely generated the greatest amount of water-cooler conversation.

Clip shows like this may not be terribly innovative, but they do have their audience. Last week’s airing of “Most Outrageous TV Moments” (7 p.m., NBC) did very well, particularly as it airs against the popular showcase “So You Think You Can Dance” (7 p.m., Fox). Indeed, success of any kind has become increasingly rare for an NBC show that does not have the words “Law & Order” in its title.

¢ After its Sunday preview, “Weeds” (9 p.m., Showtime) enters its regular time slot. The new series stars Mary-Louise Parker as a harried housewife (don’t call her desperate), who, finding herself saddled with debt after her husband’s untimely death, turns to dealing dope to fellow PTA members. The show is more provocative than funny. Why, for instance, doesn’t she move to a less-exalted neighborhood?

¢ Speaking of downsizing, “Trailer Fabulous” (9 p.m., MTV) celebrates the innovative decor of mobile homes. A repeat of last Wednesday’s “Fabulous” (8:30 p.m.) precedes this new installment.

While I hardly claim to be a trend-spotter, this is the second show this week (including HGTV’s Sunday series “Small Space, Big Style”) to accentuate the positive in less-than-palatial pads. Could the days of sprawling McMansions be going the way of the gas-guzzling Hummer?

Tonight’s other highlights

¢ On consecutive episodes of “Brat Camp” (ABC), solitude (7 p.m.), homesick for the holidays (8 p.m.).

¢ Only 007 can save the world’s gold reserves in the 1964 adventure “Goldfinger” (7 p.m., AMC), starring Sean Connnery, Gert Frobe and Honor Blackman.

¢ Even vacation cottages need poltergeist-proofing on “Ghost Hunters” (8 p.m., Sci Fi).

¢ A father-daughter impasse on “Bernie Mac” (8:30 p.m., Fox).

¢ McCoy forces the question of gay marriage onto the docket on “Law & Order” (9 p.m., NBC).

¢ A student’s brutal murder appears to be drug-related on “CSI: NY” (9 p.m., CBS).

¢ French lessons prove crucial on “Lost” (9 p.m., ABC).

¢ Some balk at the treatment of enemy prisoners on “Over There” (9 p.m., FX).