LinkedIn Corp. said it reached 100 million members Tuesday, as the professional social-networking site grows to include nearly a million teachers, dozens of Elvis impersonators and one “martini whisperer.”

The milestone comes as LinkedIn gears up for a much-anticipated initial public offering of stock expected to open the IPO floodgates for  social-networking sites.

In a company blog post, Chief Executive Jeff Weiner wrote: “We’re now growing at roughly 1 million new LinkedIn members every week, the equivalent of a professional joining the site at faster than one member per second.”

Mountain View, Calif.-based LinkedIn, which launched in May 2003, said more than half of its members, or 56 million, are based outside the United States. The company said it is seeing its fastest growth in Brazil, Mexico, India and France.

In terms of jobs listed, LinkedIn said it counted 997,000 teachers, 1,030 chocolatiers and 74 Elvis Presley impersonators, also identified by the company as “Elvis tribute artists.” The site identified one “martini whisperer.”

“My guess would be a creative way to say bartender,” spokesman Hani Durzy said in an email.

LinkedIn announced in January that it had filed a registration statement for an IPO, which is expected to trigger a wave of offerings from other social-networking sites, led by Facebook and Twitter.

Facebook, which launched in 2004, claims more than 500 million users, according to its Web site. It reached 100 million users in 2008.

Another popular site, Twitter, said it had 175 million registered users as of September 2010.

In terms of unique monthly visitors, LinkedIn had 71.5 million in February 2011, up 55 percent from a year earlier, according to comScore Inc.

Facebook had 676.7 million, up 46 percent, while Twitter had 112.2 million, up 61 percent.  MySpace had about 60.9 million, down 43 percent, according to comScore.