NEW YORK — Could a $10 coupon code buy your friendship?

It's a proposition worth considering as more retailers dangle exclusive discounts and perks on social networking sites such as Facebook and Twitter, where people stay connected by posting frequent updates about what they're doing.

You can also get the first word on special promotions, help resolving customer service disputes, or even friendly checkups on how you're doing.

In one recent Twitter post, Kmart asks about a poster's recent shopping trip, "which (store) did you go to? let me know about your trip!"

Not every company is involved in social networking and many are still figuring out how to best use the sites, but there's no doubt more are getting into the act.

Out of 100 major retailers, 59 had Facebook accounts in September 2008. That was almost double the number just four months earlier, according to Rosetta, a market research firm based in Princeton, N.J.

The discounts on Facebook and Twitter often mimic those sent in e-mail newsletters. But companies also offer exclusive deals on the sites.

Sears, for instance, sometimes gives $10 coupons to people who become fans on Facebook. Dell posts discount codes for online purchases on Twitter. Shoe retailer www.Zappos.com periodically gives passes for free overnight shipping through both Facebook and Twitter.

Some companies also use giveaways on the sites to generate a buzz.

Rather than troll for any discounts you can find, check to see if your favorite products have pages. Keeping up with a few brands you love might be a better strategy, since you never know when companies will offer coupons and deals.

The frequent updates on Facebook and Twitter can also be useful in jumping on limited-time offers.

That might be useful with sites such as DealNews.com, where about a third of listed sales expire within 24 hours, said Dan de Grandpre, the site's chief executive.

Even if a promotion lasts several days, quick action might mean snagging the size, color or model you want.

Companies generally know better than to deluge fans with updates, too.

Coupons.com, for instance, updates its Twitter account only every two to four hours, said Steven Boal, the site's founder and chief executive.

"We wanted to be very careful. You don't want to inundate people with information," he said.

To help avoid that problem, www.DealNews.com plans to segment its feed into categories such as women's clothing and electronics within the next few weeks. The idea is to tailor updates to individual interests.

But before you sign up to follow a company, be sure you know whether it's run by a fan or the company. It's usually fairly easy to tell if a page is maintained by the brand, and Facebook says it takes down unofficial pages if the company requests.

Posting questions and concerns on a public forum such as Facebook or Twitter can provoke a speedy response for obvious reasons.

"You might get a lot more success than waiting on a phone call or in line for a help desk," said Adam Cohen, a partner with Rosetta's consumer goods and retail practice.