What is it about spring that makes just about everyone on TV want to get married or have babies?

May sweeps, the four-week period when the networks throw out all sorts of special programming to try to boost ratings, has begun, and ratings determine how much can be charged for commercials.

Specifically, sweeps helps affiliates and network-owned stations.

Everything is in the networks' arsenal from a Dr.-Phil-behind-bars special to a "Law & Order: SVU" episode featuring Star Jones Reynolds and Nancy Grace.

Here are some sweeps highlights:

Guest stars

Athletes and musicians: Enrique Iglesias ("Two and a Half Men," 9 p.m. Monday, CBS); Chris "Ludacris" Bridges ("Law & Order: Special Victims Unit," 10 p.m. May 22, NBC); Mandy Moore ("Extreme Makeover: Home Edition," 8 p.m. May 20, ABC).

(Mostly) movie stars: Loretta Devine ("Everybody Hates Chris," 8 p.m. Monday The CW); Edward James Olmos ("George Lopez," 8 p.m. Tuesday, ABC); Piper Perabo ("House," 9 p.m. Tuesday, Fox); Stanley Tucci ("ER," 10 p.m. Thursday, NBC); Roy Scheider ("Law & Order: Criminal Intent," 9 p.m. May 15, NBC); Gina Gershon ("Ugly Betty," 8 p.m. May 17, ABC).

TV vets: Meredith Baxter ("Cold Case," 8 p.m. Sunday, CBS); Blair Underwood ("The New Adventures of Old Christine," 9:30 p.m. Monday, CBS); Harry Hamlin ("Law & Order," 10 p.m. May 18, NBC).

Wild cards: Maria Shriver and three real-life U.S. veterans portraying soldiers ("Brothers & Sisters," 10 p.m. May 13, ABC); Christiane Amanpour ("Gilmore Girls," 8 p.m. May 15, The CW); Rudy Giuliani and Stephen Hawking ("The Simpsons," 8 p.m. May 13, Fox); Nancy Grace and Star Jones Reynolds ("Law & Order: Special Victims Unit," 10 p.m. May 22, NBC).

Series premieres / finales

"Traveler" at 10:01 p.m. Thursday, ABC: Innocent folks on the run from the authorities in a new series billed as a cross between "The Fugitive" and "Enemy of the State."

"On the Lot" 9 p.m. May 22, Fox: A new reality series for aspiring filmmakers from Mark Burnett and Steven Spielberg.

"7th Heaven" 8 p.m. May 13, The CW: This time they really mean it. After 11 seasons and every possible wholesome story line, the Camden clan finally waves bye-bye.

"The King of Queens" 9 p.m. May 14, CBS: Everybody loves a fat man. Doug Heffernan (Kevin James) wasn't the greatest package delivery guy, but for nine years he reliably delivered laughs.

Specials

"Saturday Night Live in the '90s: Pop Culture Nation" at 9 p.m. Sunday, NBC: Another in a series of the critically acclaimed specials on "SNL's" cultural impact and highs and lows. This one features interviews with Will Ferrell, Chris Rock, Mike Myers, Tina Fey and Dana Carvey.

"The 42nd Annual Academy of Country Music Awards," 8 p.m. May 15, CBS: Reba hosts, Kelly (Clarkson) sings and everyone who is musically anyone Brooks & Dunn, George Strait, Sugarland is scheduled to be there.

"A Dr. Phil Primetime Special" at 9 p.m. May 18, CBS: The good ol' boy doc heads to prison to interview a father who is accused of locking his 9-year-old son away from the world for three years.

And other viewing

"Deal or No Deal" at 8 p.m. Sunday, NBC: It's the 100th episode, and Ozzy Osbourne makes a guest appearance. Who thought either one would last this long?

"How I Met Your Mother" at 8 p.m. Monday, CBS: Lily and Marshall finally say "I do." And no, we still don't know how Ted met his kids' mother.

"House" at 9 p.m. Tuesday, Fox: Dr. Foreman (Omar Epps) tenders his resignation. Will it be accepted?

"Law & Order: Criminal Intent" at 9 p.m. Tuesday, NBC: Days after her son mysteriously dies, so does a blond bombshell former stripper (Kristy Swanson) who was the widow of a 90-year-old billionaire. Oh come on, who'd believe such a ludicrous story line?

"Jericho" 8 p.m. Wednesday, CBS: Jericho goes to war with another town in this season finale.

"CSI" at 9 p.m. Thursday, CBS: Lady Heather (Melinda Clarke) returns. And you know how much her presence "hurts" Grissom?

"Boston Legal" at 10 p.m. May 15, ABC: Brad and Denise are getting married and having a baby. Not necessarily in that order.