TODAY'S MUST-SEE

"Mad Men," 2 p.m., AMC. This series has drawn waves of praise and 16 Emmy nominations. Still, it's so subtle that new viewers are perplexed. Here's a solution: Catch up on the entire second season (so far), concluding with a new episode at 7 p.m. There are a few major moments — an airline crash at 3 p.m., a car crash at 6 p.m. Mostly, however, this quietly views a 1962 ad agency and the illusions that enshroud its people. The new episode, at 7 p.m., involves an effort to give Playtex the sort of zesty ads that Maidenform has. It's also about more; clouds of despair descend in surprising ways.

TODAY'S MIGHT-SEE

"CSI: NY," 9 p.m., CBS. With the political conventions airing, many 10 p.m. shows have been missing. CBS scheduled one of them ("Flashpoint") for tonight, then switched to this "CSI:NY" rerun. The victim had built a giant ark.

OF NOTE

"Clean House," 6, 7:30, 8, 9 and 10:30 p.m., Style Network. What happens after a reality show has created its transformation? Some of the "Clean House" families kept their homes tidy; others were wretched backsliders. In its 100th episode (which has more noise than wit), there are "awards" for both extremes.

"Extreme Makeover: Home Edition," 7 p.m., ABC. Here are two projects dealing with Louisiana flood victims. One rebuilds a home, the other a church building.

"National Treasure" (2004), 7 p.m., NBC. Nicolas Cage stars in this popular film, playing an adventurer who believes clues to a treasure can be found on the back of the Declaration of Independence.

"The Simpsons," 8 p.m., Fox. Bart has a new cohort.

"Cold Case," 8 p.m., CBS. This rerun offers a variation on the usual, long-ago case. Last year, someone was allegedly kidnapped from her engagement party and killed. Now Lily and Valens must take the suspect back to Philadelphia from West Virginia.

"Desperate Housewives," 9 p.m., ABC. It's full-scale war between Bree and Edie. Also, Susan's mother-in-law visits.