Casting calls continue in San Francisco and Chicago on “American Inventor” (8 p.m., ABC).

The patent office variation on “American Idol” enjoyed strong ratings last week, due in large part to the absence of the dominant CBS lineup of “Survivor,” “CSI” and “Without a Trace.” What’s not to like about “Inventor”? OK, the proliferation of bathroom-related gadgets is a tad disturbing, but any series that puts an accent on thinking and ingenuity can’t be all bad.

¢ Speaking of ingenuity, the new, imported British comedy “Ed vs. Spencer” (10 p.m., BBC America) puts a British spin on “Jackass”-style pratfalls. Cameras follow two slackers as they participate in seemingly random and pointless competitions, such as “who can lose the most weight?”; who can get the most female attention?”; and “who can stay handcuffed the longest?”

Ed and Spencer take very different approaches to their demented contests. Diligent Spencer appears to believe in research, hard work and preparation. Ed has the confidence of a decadent natural. In tonight’s debut debauch: “Who can get the sickest?” Spencer consults medical journals and experts, exposing himself to the extreme cold of meat freezers, gets himself bit by a snake and tries to induce a homemade case of athletes’ foot. Ed goes about it the old-fashioned way: drinking and smoking to excess, staying up all hours and passing out in the street, hanging out in bars and picking pointless fights. Guess who wins?

¢ “The Showbiz Show with David Spade” (9:30 p.m., Comedy Central, TV-14) enters its second season. The “Saturday Night Live” alumnus provides snarky commentary on the week’s doings in movies and television, with the emphasis on the vain excesses of the boldfaced name set. More interesting for its audaciously low-budget production values than its insights.

Tonight’s other highlights

¢ The NCAA Basketball Tournament (6 p.m., CBS) continues. A second game (8 p.m.) follows.

¢ Catherine Zeta-Jones, Renee Zellweger, Richard Gere and Queen Latifah star in the 2002 musical “Chicago” (7 p.m., Bravo).

¢ Katrina victims need help on “Extreme Makeover: Home Edition” (7 p.m., ABC).

¢ After Rochelle’s father (Jimmie Walker) dies, everyone worries about her seemingly casual attitude on “Everybody Hates Chris” (7 p.m., UPN).

¢ A karmic quest brings back memories of Y2K on “My Name is Earl” (8 p.m., NBC).

¢ Seth and Summer need help on “The O.C.” (8 p.m., Fox).

¢ Sharon Lawrence, Mika Boorem and Tim Matheson star in the 2006 made-for-TV drama “Augusta, Gone” (8 p.m., Lifetime), about a teen’s life shattered by drug use.

¢ Dwight’s executive decision imperils the medical plan on “The Office” (8:30 p.m., NBC).

¢ A stabbing victim may not survive the wait for a surgeon on “ER” (9 p.m., NBC).