* Medium (9/8c CBS)
Psychic drama mama Allison DuBois does the time warp. The series takes a bounce back in time to Allison and Joe's nuptials, a special day that finds the couple prepping for their big "I do" moment. But even as she opens this new chapter in her life, Allison sees her paranormal gift coming into play, and she's forced to face up to its ever-expanding powers. Bruce Gray and Kathy Baker return in their roles as Joe's parents. Actor David Paymer directed the episode.
* Numb3rs (10/9c CBS)
The show's number may be up. The sixth season concludes with Charlie and Amita getting married and heading off to England, where they will begin teaching at Cambridge. They needn't hurry back. CBS hasn't officially canceled the series, but it only ordered 16 episodes for the sixth season and, after airing two weeks of college-basketball playoffs beginning next week, is launching Miami Medical on Friday, April 2, at 10/9c. For NUMB3RS fans, it all adds up to zero.
* Supernanny (9/8c ABC)
If you've ever wondered what happens when Jo Frost says good-bye at the end of an episode, be sure to check out tonight's sixth-season finale as she checks in with families from years past in a trio of emotional reunions. It also marks the series' 100th show, a milestone mirrored by how far these folks have come, especially a woman from Season 5 who lost her husband to cancer just a few weeks before Jo's visit, and had to raise two young children on her own.
* Who Do You Think You Are? (8/7c NBC)
In the second episode of a seven-part profile series that charts a celebrity's lineage, sports analyst and former football player Emmitt Smith takes the ball and digs into the roots of his family tree. Driven by a rumor that his grandmother may have had white ancestry, Emmitt goes the extra yard to explore details. His investigative travels direct him deep into Alabama, colonial Virginia and beyond, resulting in the revelation of a dramatic family history.
For nearly a century, the Girl Scouts of the USA have made a (Thin) mint selling their famous cookies. But in the first half of this episode, Tim thinks he's found a way for a boy-scout troop to equal the profits of their distaff counterparts. In the second cartoon, it's a toss-up whether Rodney's co-workers are more surprised by the fact that he's married or that he suspects his wife is cheating on him with a hockey player. In any case, it's up to Tim to get to the bottom of this mystery.