While you’re out shopping, caroling or enjoying some eggnog this holiday season, the networks still have a job to do.

In years past, the end of the November sweep sent the broadcasters into hibernation for the rest of the year. Viewing levels drop and cable networks would steal the spotlight via holiday stunts like ABC Family’s “25 Days of Christmas” marathon, creating what one network exec calls “a dead zone” for the Big Four.

But now, just as summer has long served as an incubator for new reality series, December has become a place for the networks to experiment.

“Why not?” says an exec. “Somewhere along the way if you have a fun project that you’re not quite willing to expose in the regular season, here’s this little hammock where the pressure is off. Why not take a shot?”

That means — in addition to a growing slew of holiday specials — auds can expect to see a roster of limited-run reality series tryouts.

This year ABC, NBC and Fox have all scheduled such shortform programming during December as a way to test out concepts and stir up viewer interest in a month with relatively few original episodes of top series.

That makes December in many ways a mirror of the networks’ summer strategy. As repeats no longer make sense for many shows (given their rock-bottom ratings), the networks have been freed, to some degree, to use timeslots in low-rated weeks of the year to experiment with other programming.

Many of these shows are also set to air at 8 p.m., when the pressure’s even lower, yet there’s a greater chance that families, home for the holidays, are watching TV together. Giving them an easy-to-digest unscripted show — rather than repeats of other fare — might very well mean the networks get a little something extra in their Nielsen stocking.

The strategy has brought success in the past: NBC launched gamer “Deal or No Deal” as a December strip in 2005 and went on to a successful run in primetime (and later, syndication).

Others haven’t fared so well: The 2007 December entry “Clash of the Choirs” didn’t catch on.

This year at NBC, the network is bringing back “The Sing-Off,” hosted by Nick Lachey, for a second season.

The a capella singing competish will air five times, on Mondays and Wednesdays the first two weeks of the month, with a finale Dec. 20. This will allow the net to avoid repeats of “Chuck,” already a marginal performer in originals.

ABC, meanwhile, will take advantage of both the holidays and the break between its “Dancing With the Stars” finale

and the January return of “TheBachelor” to air “Skating With the Stars” on Mondays. As aresult, the Alphabet will be in originals on the night, with femme-focused reality skeins virtually every week of the season.

The new show — essentially “Dancing With the Stars on Ice” — runs from Nov. 22 through Dec. 20, with a finale Dec. 21. And over at the Fox, the net is hoping to conjure up a little “Deal or No Deal” mojo by launching new gamer “Million Dollar Money Drop” in much the same fashion.

Just as NBC bowed “Deal” (from Endemol USA) as a week-long Christmastime event in 2005, Fox will do the same this year with “Drop” (also from Endemol).

“The last time one of these shows clicked was ‘Deal or No Deal,’ which rolled out with almost the exact same dates,” says Fox alternative prexy Mike Darnell. “Obviously some of the networks have tried over the past few years. This is our first attempt, and the only real stripped attempt this year.”

“Million Dollar Money Drop” will air on Fox from Monday, Dec. 20 through Thursday, Dec. 23. Hosted by Kevin Pollack, the gamer follows a pair of contestants who are given $1 million and then asked a series of multiple-choice trivia questions. They place their bets on a trap door that represents their choice, and can hedge their bets by splitting their cash between all but one of the doors.

If their answer turns out to be wrong, the trap door opens and their money is gone. Contestants keep playing through seven questions, or until all their money has fallen down the “drop.”

That’s an image many viewers — having just racked up credit card bills for pricey holiday gifts — will likely relate to.