For former celebrities, particularly former child stars, the cruelest words in the English language must be “Where Are They Now?” (7 p.m., VH1). But given cable television’s insatiable hunger for continual pop-cultural recycling, it’s getting harder for old favorites to fully mature into full blown has-beens. After all, hasn’t Gary Coleman been goofing on his old “Diff’rent Strokes” character for most of his adult life? It has been only seven years since “Blossom” went dark. Have Mayim Bialik and Jenna Van Oy really had time to suffer rerun nostalgia?

Apparently, they do. And so do Todd Bridges (“Diff’rent Strokes”), Willie Aames (“Eight is Enough,” “Charles in Charge”), Emmanuel Lewis (“Webster”), Candace Cameron (“Full House”) and Alison Arngrim (“Little House on the Prairie”). We’ve all seen and heard this before. And some of us can’t get enough.

Man’s best friend also happens to be one of the world’s best detectives. The one-hour special “Nose For Crime” (7 p.m., Animal Planet) explores the world of K-9 detectives and canine rescue teams. The pooches profiled here have some seriously scent-sational snouts. One chocolate Labrador can detect a body hidden in a watery grave 64 feet below the ocean’s surface. We also meet a trained arson dog who can detect a tear-sized particle of fire accelerant in an area as big as a football field. “Nose” also examines the kind of human detectives who work best with dogs.

Alan Alda travels to the innovative Media Lab at the Massachusetts Institute of Technology to host “The Intimate Machine” on “Scientific American Frontiers” (8 p.m., PBS). There he interviews several scientists who are working on new programs that might someday enable a computer to react to its user’s voice and hand gestures and even make eye contact. One scientist is working on a kind of cyberbutler who can anticipate its owner’s needs. It will call up the morning newspaper, answer a knock at the door and even find a set of lost keys.

While some of these dreams may conjure images of Big Brother or HAL from “2001,” some of the current interactive computer personalities are decidedly quirky. A robot named REA takes an instant dislike to Alda and shuts down whenever he speaks.

Tonight’s other highlights

Lorelai’s folks meddle when she dates a man from a posh family on “Gilmore Girls” (7 p.m., WB).

Giants vs. Angels in Game 3 of the World Series (7 p.m., Fox).

Alvin loses his job after being caught in a sordid situation on “The Guardian” (8 p.m., CBS).

The daughter of a victim of Sept. 11 appears in a custody case on “Judging Amy” (9 p.m., CBS).

A bicycle theft ends in a stabbing on “NYPD Blue” (9 p.m., ABC).

Series notes

A jet maintenance worker faces murder charges on “JAG” (7 p.m., CBS) … Real-estate wars on “The In-Laws” (7 p.m., NBC) … Cheerleading woes on “8 Simple Rules” (7 p.m.) … Anya casts a monstrous spell on “Buffy the Vampire Slayer” (7 p.m., UPN) … Nina dates a rock icon on “Just Shoot Me” (7:30 p.m., NBC) … Jim and Cheryl adopt the pizza delivery boy on “According to Jim” (7:30 p.m., ABC) … The perfect proposal on “Frasier” (8 p.m., NBC) … Bonnie feels unattractive on “Life with Bonnie” (8 p.m., ABC) … Temporary blindness on “Haunted” (8 p.m., UPN).

Late night

Bruce Springsteen and the E Street Band and Mitch Hedberg appear on “Late Show with David Letterman” (10:35 p.m., CBS) … Jay Leno welcomes Kate Hudson, Elon Gold and BB Mak on “The Tonight Show” (10:35 p.m., NBC) … Sarah Michelle Gellar, Larry Hagman and the Hives are booked on “Late Night with Conan O’Brien” (11:35 p.m., NBC) … Ted Danson and Jessica Biel are booked on “The Late, Late Show with Craig Kilborn” (11:37 p.m., CBS).