“Idol Gives Back 2008” (7:30 p.m., Fox): Simon Cowell’s trademark scowl takes a

“Idol Gives Back 2008” (7:30 p.m., Fox): Simon Cowell’s trademark scowl takes a hiatus in tonight’s extended telecast to raise money for a variety of charities. Bono, Mariah Carey, Miley Cyrus, Brad Pitt, Reese Witherspoon, pro football’s Manning brothers and several former “Idol” contestants are among the celebrities scheduled to appear live. Host Ryan Seacrest takes his usual spot on the “American Idol” stage, co-hosting with Ellen DeGeneres from the Kodak Theatre in Los Angeles. The pair teamed up for a similar benefit last year, which raised $76 million for a range of causes.

“Drafting Partners” (9 p.m., GAC): Country stars such as Jason Michael Carroll learn the ropes of NASCAR from drivers such as Jeff Burton.

“Primetime Special: The Last Lecture: A Love Story for Your Life” (10 p.m., ABC): Diane Sawyer reports on how people change their lives when faced with terminal illness. She spotlights Carnegie Mellon professor Randy Pausch and his family. Pausch, who has been diagnosed with pancreatic cancer, wrote a book titled “The Last Lecture,” which explores topics such as leaving a legacy and enabling others to fulfill their dreams.