JIM and Noel Johnston cheered like their Parisian neighbors when Lance Armstrong pedaled past them to his seventh Tour de France victory last year. In London, they shopped at the local butcher shop and attended the theater like longtime residents, then enjoyed a getaway to a 16th century stone cottage in the Cotswold district. Another time, they piloted a private Boston Whaler like natives through Amsterdam's canals to reach their favorite waterfront restaurant.

The Johnstons don't own properties in these cities or even the boat; they just act as if they do. They are seasoned house-swappers, exchanging their L.A. beach home in Venice with people around the world. They stay four to six weeks in the nicest neighborhoods without having to pay for lodging. They trust that the people watching their white-walled, art-filled condo are being as responsible with it as the Johnstons are with their home.

The best part of the vacation experience, however, is that they never feel like tourists.

"Staying in someone's home is a wonderful way to experience a different city. It's like stepping into someone else's life," says Jim Johnston, a retired film producer. "Some people are funny about sleeping in a stranger's bed or having a stranger sleep in theirs, but I'm not against wearing someone else's shirt if he's my size. Several of the people we've exchanged with have become friends."

The Internet has made it easier to find people willing to swap. Free listings, such as those on Craigslist, or those that charge about $50 to subscribe allow people to post descriptions of their homes and search a directory for a house to swap that meets their needs or dreams. Homeowners then contact each other to hammer out the details: dates, responsibilities (pet care?), housekeeping styles (Oscar or Felix?) and a hands-off list (car?).

Membership in Intervac, an exchange service with an office in the Bay Area, has increased 40% in the last two years, says spokeswoman Jessica Jaffe. "Home exchanging seems to be on the rise, probably due to the price of hotel accommodations, which are hugely expensive in Europe, and the dollar-to-euro exchange, which is historically poor."

Exchangers reimburse each other for long-distance telephone charges and other expenses, but there's no cost to snooze in someone else's recliner, have temporary access to the mailbox, computer and golf clubs, and even buddy up with the friendly neighbors.

The Johnstons, who also own a second home in Telluride, Colo., have used two of the oldest exchange services, Intervac and Homelink, for five years. "Nothing has ever been broken, taken or damaged," says Noel Johnston, who locks valuable and sentimental items in a storage closet.

One person spilled a drink on the rug and offered to pay for the cleaning when she couldn't get the stain out. Says Noel Johnston with a shrug, "A meticulous person might not be able to handle this, but it works for us."

Jim Johnston laughs about items that have been left behind by visitors: A Dutch family left Dutch beer, black bread and brown eggs. An English couple stocked the refrigerator with burrata cheese, yogurt and champagne. A French family left behind instant mashed potatoes, frozen dinners and frozen vegetables: "So much for French cuisine," he says.

The Johnstons have experienced two drawbacks to exchanging: The apartment in Paris, like so many there, was 900 square feet, a fraction of the space the traders received on the boardwalk in Venice. "That time it was not really equitable" in terms of living space, he says, "but other times we have had a great deal."

The Johnstons have heard a few tales about exchanges that have gone wrong. A couple they knew arrived in Los Angeles to find that the family they were to trade with had changed their minds. "The exchange service stepped in to help the out-of-towners find a place to stay and they took the reneging family off their list," says Noel Johnston. She also learned of a couple that wasn't told about construction nearby. She has avoided surprises by e-mailing and phoning the other family until she's satisfied she has all the information and "knows their personality."

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Where to go online to trade spaces

Some services that offer properties for swap worldwide. Exchange properties vary from houseboats and RVs to modest apartments and lavish estates.

Craigslist: Free to post and access home exchange listings, which span from Bakersfield to Zurich; http://www.craigslist.com .

Digsville: About 4,000 listings. Site allows members and guests to contact each other. Listings $44.95 per year. P.O. Box 5185, Hoboken, NJ 07030; (877) 795-1019 or (201) 864-7455, http://www.digsville.com .

Global Home Exchange: 500 to 700 listings. Nonmembers can access contact information. Listings about $17 for 24 months. 6140 Kirsten Drive, Nanaimo, BC, Canada V9V 1J7; (250) 756-6177, http://www.4homex.com .

Green Theme International: About 2,000 listings. Based in France and the United Kingdom, it offers Web pages in several languages. Only members can access contact information. Listings $30 per year. 9 Rue des Insurges, 87130 Linards, France; 011-33-555-084-704, http://www.gti-home-exchange.com .

Holi-Swaps: Founded in England, expanded into U.S. in 2001. About 500 listings, most in Britain, Australia, Canada and the U.S. Nonmembers can access contact information. One-year membership, $35 and two years, $59.95 for unlimited swapping. 9319 N. 94th Way, #500, Scottsdale, AZ 85028; (602) 604-1529, http://www.holi-swaps.com .

Home Base Holidays: About 3,000 listings, many in Britain (none more than 2 years old). Only members can access contact information. Listings about $47 per year. 7 Park Ave., London N13 5PG, England; 011-44-20-8886-8752, http://www.homebase-hols.com .

HomeExchange: 8,500-plus listings. Listings and contact privileges, $50 per year; contact access only, $20. Nonmembers can view listing information. Box 787, Hermosa Beach, CA 90254; (800) 877-8723 or (310) 798-3864; http://www.homeexchange.com .

HomeForExchange: About 2,900 listings worldwide, growing monthly. First-year membership is free; second year, $48 (less each renewing year). Listings are public, but only members can contact other members. 15a Laarstraat, Zutphen, The Netherlands, 7201 CA; http://www.HomeForExchange.com .

HomeLink: More than 14,000 listings. Only members can access contact information. Listings $80 a year for Web only; $125 for Web plus printed directories. 2937 N.W. 9th Terrace, Wilton Manors, FL 33311; (800) 638-3841 or (954) 566-2687, http://www.homelink-usa.org .

International Home Exchange Network: About 3,000 listings. Nonmembers can access contact information. Listings, $39.95 a year. 118 Flamingo Ave., Daytona Beach, FL 32118; (386) 238-3633, http://www.ihen.com .

Intervac: About 12,000 listings, most outside the U.S. Only members can access contact information. Listings start at $65 a year for Web only, $140 for Web plus printed directories. 30 Corte San Fernando, Tiburon, CA 94920; (800) 756-4663, http://www.intervacUS.com .

The Invented City: About 2,000 listings (mostly outside of North America). Annual fee, $50 a year. (415) 846-7588, http://www.invented-city.com .

Réseau International d'Échange de Foyers: Several hundred listings. Direct contact to members available to everybody. Listings, message board and mailing list are free. Translation of listings from English, French or German is $25. Creux de Corsy 55, CH-1093 La Conversion, Switzerland; 011-41-79-341-5761, http://www.exchange-of-homes.com .

The Vacation Exchange Network: 1,200-plus listings. For vacation properties (second homes) only, so exchange need not be simultaneous. Membership is free the first year and $29.95 per year for renewal. P.O. Box 277, Whippany, NJ 07981- 0277; (800) 266-3644 or (973) 386-9208, http://www.thevacationexchange.com .

Vacation Homes Unlimited: About 3,500 listings. Free database previews. Only members can access contact information. Listings, $30 a year. 16654 Soledad Canyon Road, Suite 214, Santa Clarita, CA 91387; (800) 848-7927 or (661) 298-0376, http://www.exchangehomes.com .

— Janet Eastman