Procter & Gamble Co., the largest U.S. maker of household products, plans to sell almost 100 Internet domain names through GreatDomains.com, a Chatsworth auction site. The maker of Tide detergent and Crest toothpaste said it will sell flu.com, beautiful.com, thirst.com and other names that it has acquired since 1995, but has since decided not to develop into Web sites. Internet domain names for its 300 product brands aren’t for sale, Procter & Gamble said. Desirable names such as flu.com, which could attract interest from drug companies, might sell for well over $1 million each, said Jeff Tinsley, CEO of GreatDomains.com. “These are some of the most valuable properties available on the Internet,” Tinsley said. Officials of Cincinnati-based Procter & Gamble were surprised by the high appraisal value put on its names, said spokeswoman Terri Carrick. Prices for Internet domain names have been falling since business.com fetched a record $7.5 million in November from Santa Monica-based eCompanies. “We expect the returns to be great, though incremental in the large picture of things” for a company with $38 billion in annual sales, Carrick said. Procter & Gamble registered the names for nominal fees, she said. The average price for domain names sold in May was $27,565, way down from an average of $52,298 for the past seven months, according to GreatDomains.com. The Chatsworth company operates sort of like a real estate agency which is to say, it doesn’t own Web addresses itself, but serves as a broker in marketing the names and finding buyers. If the name sells, GreatDomains.com takes a commission ranging from 7 percent to 10 percent of the purchase price. It hit gold last year with the name drugs.com, which was sold to a San Francisco-based startup running an Internet pharmacy. The name was sold for $823,000, and GreatDomains collected a 10 percent commission. Other valuable names brokered through the site include loans.com, houses.com and shoppingmall.com. GreatDomains allows anyone to list any name for sale, but once actual bidding comes in for a particular name, it does a background check to make sure the name is legitimately owned by the seller and that the buyer has the financial wherewithal to pay the bid price. For big-ticket names, background checks are conducted prior to the name being listed.