ATLANTA — Melinda Irwin already travels plenty, so using the frequent flier miles piling up in her Delta Air Lines Inc. SkyMiles account for more airplane tickets didn't really appeal to her.

That's why the Oklahoma City travel agency owner instead bid her miles in an online auction last month for a chance to build homes for Habitat for Humanity.

Irwin bid 118,500 SkyMiles to win one of three "voluntourism" trip packages. The package includes travel for two between New York and Mumbai, India, seven nights of lodging and a chance to build homes with 40 Delta employees in Maharashtra, India.

The Atlanta-based airline will donate the miles from the winning bidders to the nonprofit organization.

"Normally it's retired people that choose to do this sort of thing because they have the disposable income and free time, but I don't want to wait until I'm retired to do all this stuff," said Irwin, 41, who will take the trip with her husband, Dale Frey. "Since I'm in the travel business, I have the opportunity to do the other stuff, so this is something extremely unique ... that I probably would have never chose to go on my own."

The Atlanta-based airline introduced auctions earlier this year as a way to use SkyMiles, focusing on hard-to-come-by events such as front-row concert tickets with backstage access or an Atlanta Braves baseball game that includes a meeting with players.

Delta joined a growing number of airlines and hotels that also have frequent traveler points auctions. Since 2002, Houston-based Continental Airlines Inc., for one, has been offering items such as autographed NFL jerseys on its auction site.

"This is just another opportunity for customers to use their miles, just a little different way than travel. It's been extremely popular with customers," said Continental spokeswoman Mary Clark.

Starwood Hotels & Resorts — which runs hotels that include the Sheraton, St. Regis, Westin and W brands — offers auction trips to Malaysia, VIP access to the American Music Awards or a trip to the Los Angeles set of the television show "Las Vegas."

Delta dreamed up the volunteer trip after officials decided it would be a good way to combine the auction with the airline employees' volunteer program, Delta Force for Global Good, which has a goal of building 100 homes in India.

"We're finding alternative ways for customers to use frequent flier miles rather than just buying airline tickets," said Jeff Robertson, managing director of the SkyMiles program.

"It helps open people's eyes to what poverty housing means outside the United States," said Habitat spokesman Chris Clarke. "About 22 percent of the world's poor is in India, and we think it's a good place to demonstrate to Delta and their customers what their support can do in changing a community."

Airline officials said they have been impressed by the response to the volunteer package, as 51 people placed bids.

When Tara Dryg of Kaysville, Utah, saw the auction site, the Habitat trip immediately interested her.

"It's been kind of a dream to work with Habitat, so right away I was interested," said Dryg, 31, one of the three auction winners. "What put me over the edge was when I read Delta was not only taking part but donating the winning SkyMiles to Habitat."