Trading cards has long been a popular hobby. Trading stocks drives the world's economy. But the new thing is Trading Spaces.

With upwards of 3 million people tuning in every weekend, according to the Nielsens, TLC's series Trading Spaces is a surprise hit not only with women — its target audience — but with men and children too.

"There are so many different ways to latch onto the show," said Paige Davis, the show's host. "Kids love it for the drama, women love it for all of the home decorating, men love it because it's kind of a sporting event — there are rules, there's jeopardy."

The show is based on the British hit Changing Rooms, where two sets of neighbors redecorate a room in each others' home with the help of an eccentric decorator and a hunky furniture designer, all on a budget of $1,000.

Critics see the show's success as a natural succession of already proven TV staples.

"We've had many years of makeover segments and they have always done very well," said Robert Thompson, a popular culture expert from Syracuse University. "This is like reality TV meets the makeover segment."

Waiting for something crazy to happen or just getting some decorating tips keeps viewers coming back for more.

"I love it when (participants) are brave and they're willing to take the risk," said Davis. "They're not just signing up because they want to get a free room. They're signing up because they want to break out of their mold and do something like paint a wall bright red or do something crazy."

But the drama during the "reveal" part of the show — when couples see how their room has been redecorated — is the big payoff. Participants' reactions have ranged from shouts of glee to cries of disappointment at the end of the 48-hour process. Some unhappy participants have even filed lawsuits against the show.

"Usually it's tears of joy, but the ones that are really, really upset are just not ready for the change," said Davis, who was in New York recently promoting 100 decorating tips for under $100 compiled by Visa.

She said the show emphasizes innovative ideas and encourages people to think out of the box.

"Take this idea of towels (rolled up in) a wine rack. It's taking everyday things and seeing them in a new way," said Davis. "Color is also a big thing on Trading Spaces. It's the number one way to put impact and personality in any room of your home. I suggest being bold."

And apparently audiences love to see those bold choices. TLC is increasing the number of shows from 45 to 60 for Trading Spaces' upcoming third season in order to capitalize on its cult-like popularity.

"It's evidence once again how cable has become the test kitchen for new ideas in TV," said Thompson. "We may never have seen a show like this on TV without cable. But you can bet network people take notice of how it's doing."