The audition round wraps up on “America’s Got Talent” (8 p.m., NBC), but not before Meredith Vieira interviews Susan Boyle, the surprise Internet sensation from “Britain’s Got Talent.” Parts of Vieira’s chat with Boyle can also be seen on “Today” (6 a.m., NBC).

The worldwide interest in Boyle and the enduring popularity of “America’s Got Talent,” the summer’s top-rated show, cannot be dismissed. “Talent” re-creates the hit-and-miss quality of old vaudeville and TV variety shows and continues a TV tradition that can be traced from “Idol” to “Star Search” to “Ted Mack & the Original Amateur Hour” and radio’s “Major Bowes Amateur Hour,” the show that discovered, or at least popularized, a Hoboken, N.J., crooner named Frank Sinatra.

The tradition of thrilling to undiscovered talent and booing atrocious pretenders probably dates back to the amphitheaters of ancient Greece. But there may be a contemporary urgency to our embrace of “Talent” — the proliferation of untalented nonactors on reality television.

Cable networks nibble away at niche audiences with vain and vulgar freak-show attractions called “Real Housewives” and Heidi and Spencer and Jon and Kate. People who become celebrities solely because of their obnoxious behavior may appeal to the cynical, bored or merely lazy, but the explosion of giddy excitement and tears of joy over Susan Boyle’s triumph tells us that the sudden discovery of real but hidden talent appeals to something larger and nobler in the human heart.

• Soledad O’Brien hosts “Black in America 2” (7 p.m., CNN), a multipart report. “Today’s Pioneers” (7 p.m.) profiles community organizers in the public and private sectors as well as writer/actor/producer Tyler Perry, who has created an entertainment industry with his plays, movies and (critic-proof) TV sitcoms. “Tomorrow’s Leaders” (10 p.m.) interviews young African-Americans in business and academia.

• “Wide Angle” (9 p.m., PBS, check local listings) profiles Eleni Gabre-Madhin, an Ethiopian-born economist raised and educated in the United States. Together with other Ethiopian exiles, she returned to her native country to help establish a modern market and commodities exchange for corn, sesame, coffee and grains.

Horrified by the drought and famine of the mid-1980s that killed more than a million people, she believes that much of the suffering stemmed not from lack of food but from a chaotic trading system rife with corruption, inefficiency and mistrust.

This may sound rather dry, but it offers an eye-opening lesson in very basic economics and the liberating aspects of free and fair trade. Aaron Brown, formerly of CNN, anchors this report.

• Speaking of markets, Charles Gibson hosts the ABC News special “Over a Barrel: The Truth about Oil” (9 p.m., ABC).

Tonight’s other highlights

• The top eight perform on “So You Think You Can Dance” (7 p.m., Fox).

• A crooked promoter faces a fight on “Leverage” (8 p.m., TNT).

• “Repossessed: Hard Times” (8 p.m., National Geographic) shows how recessions can be boom time for “repo men.”

• Teddy takes a crack at the Balkans on “The Philanthropist” (9 p.m., NBC).

• Contestants at the University Royalty Pageant in Texas learn to vamp before they can walk in the season-two premiere of “Toddlers & Tiaras” (9 p.m., TLC).