Facebook was the third most-visited destination of Internet users over 65, trailing behind Google and Windows Media Player, according to a November survey conducted by The Nielsen Company.

Only a year ago Nielsen reported that, for the 65 and over demographic, Facebook was much further down on the list of most-visited sites, ranking 45.

Usage of social networking and blog sites for this age group has increased 53% in the past two years and comprise 8.2% of visitors to these sites, Nielsen reported.

As previously discussed here, women in the senior demographics have led Facebook growth for much of this year, according to Facebook’s self-reported data, at least from February through September. Nielsen alsoreported that female Internet users outnumber men in this age group, similar to patterns of Facebook use we previously reported.

In February, Facebook’s fastest-growing segment was women over 55, although the men in that age group weren’t flocking to the site in nearly the same numbers. This trend continued into September when many more women aged 45-65 were joining Facebook than men that age, with nearly twice as many women over 55 than men.

Last month female users continued to dominate Facebook, totaling 56.1% of users.

Nielsen noted a similar pattern with Internet usage, “Among people 65+, the growth of women in the last five years has outpaced the growth of men by 6 percentage points.”

Why should marketers care about the 65 and older online crowd, which Nielsen reported totals just 17.5 million, as of November?

Well, this age group comprises 13% of the population and tends to have both more disposable income and leisure time than other demographics.

In others words, they have more money to spend and more time to browse than others. And given the rapid growth of Facebook use among this population, there’s potential to cultivate this surging market.