Hike With Your Dog.com, www.hikewithyourdog.com. The "Park of the Month" archives detail the doggy life in a particular U.S. park each month (with links), and you can search for dog-friendly hikes by state. Other pages suggest relevant books and give advice on traveling with dogs. Also offers "Hike With Your Dog" tours of the mid-Atlantic region.
Pet Friendly Travel.com, www.petfriendlytravel.com. Lodging listings in the United States and Canada focus on condos, cabins and private homes that allow pets. Listings provide info on local activities and special pet-friendly amenities.
Pet Travel Inc., 954-684-9535, www.pettravel.com. Worldwide lodging info with 19,128 listings. Also, comprehensive info on immigration laws, airline policies and pet-friendly restaurants.
Pets on the Go, 781-934-7202, www.petsonthego.com. Pet-friendly hotels, destination reviews and other resources on the info-packed site. Membership ($15 annually) allows you to customize your search and access premium content.
Pets Welcome.com, 845-297-5150, www.petswelcome.com. Excellent listings on a variety of pet-friendly lodgings, info on international travel and tips on dealing with emergencies. New this year: "Hurricane Info Exchange" forum. The "Search by Route" feature allows you to see pet-friendly lodging between your starting point and final destination.
AARP, 888-687-2277, www.aarp.org. Popular advocacy group offers great travel discounts among its other services. Membership (50 and older only) is $12.50 a year.
Elderhostel, 877-426-8056, www.elderhostel.org. Nonprofit group organizes adventures for almost a quarter-million travelers over 55 each year. Take the grandkids on one of the Intergenerational programs, or check out the associated Road Scholar program at www.roadscholar.org.
Grand Circle Travel, 800-553-1129, www.gct.com. This company markets tours and cruises specifically to the over-50 set (but all ages welcome), and efforts are made to limit single supplements for solo travelers. The tours have a reputation for being unhurried and immersing travelers in local culture. The Overseas Adventure Travel division offers trips a bit bolder than those under the Travel division.
Hostelling International USA, 202-783- 6161, www.hiusa.org. This site covers low-cost lodging in the United States, with links to hostel information in more than 60 countries available to people of all ages, not just grungy backpackers. Membership for those 55 and over is $18 a year (normally $28 a year) and includes international travel insurance coverage and discounts on Greyhound.
National Association of Retired Federal Employees, 800-627-3394, www.narfe.org. Group for federal retirees and their families offers travel discounts among its perks. Membership is $25 a year plus local chapter dues if you join before retiring, $33 annually after retirement.
Senior Summer School, 800-847-2466, www.seniorsummerschool.com. Mostly two- to six-week summer educational programs with classes and lectures in political science, art, etc. The sessions are at 11 universities in the United States and Canada, with Atlanta added as one of this year's seven-day New Year's trips.
Connecting: Solo Travel Network, 800-557-1757, www.cstn.org. Helps solo travelers find compatible traveling partners through a bimonthly newsletter and offers tips on single supplements and other downsides of solo travel. Full annual membership is $45 ($28 for Internet-only membership).
Going Solo Travel Club, 888-446-7656, www.goingsolotravel.com. Offers international tours for single travelers -- married folks are welcome as long as the spouse is left behind -- and matches travelers with roommates to avoid single supplements. No membership fees.
O Solo Mio Singles Tours, 800-959- 8568, www.osolomio.com. Travel club of group trips for individuals -- no "fuddy duddies" allowed. It aims to arrange roommates for those who want them, but it's not guaranteed.
Singles Travel International, 877-765- 6874, www.singlestravelintl.com. Agency guarantees you a roommate on its singles-only trips -- or it will pay for the single supplement itself. Also offers single-parent trips where kids are welcome.