Social recommendations are becoming an important component of online marketplaces. They keep popping up in new and different ways.

So far, I’ve identified 4 ways that social recommendations are used to build trust in marketplace transactions:

1. To highlight affiliation between buyer and seller

Example: Airbnb, the online marketplace for short-term vacation rentals, identifies host affiliation in search results if buyer and seller have a university in common i.e. “This host also attended Harvard University.”

2. To identify seller as “in-network”

Example: Airbnb links to your social networks to be able to identify whether you and the host have any connections in common.

3. To offer & validate personal details

Example: Airbnb incorporates social information to make the transaction more personal – each person creates a profile with a short biography, a photo, and the choice to link to linkedin, facebook, pull in work history, education, your photo, etc. The largest benefit is that the person’s biography can be corroborated by ‘school’ and ‘work’ details that are pulled in from social networks.

4.  To “automate” the referral process

Example: Urban sitter, an online community of parents and babysitters, makes it easy for parents to find facebook friends on the site and get referrals to sitters they trust.  (Note: My profile isn’t a great example of the potential of this referral system given that most of the people in my facebook network do not yet have children. However, you can imagine how useful this would be for someone in the right “life stage”!)

What’s next for social recommendations?

There is a big opportunity for social recommendations to expand to the broader world of online marketplaces. For example, I’d like to see Apple implement this in the App store – next time I search for a productivity app, rather than select based on ratings alone, I’d like to see what my tech-savvy friends are downloading.

Noticeably absent from sites like Etsy.com, I expect a number of online marketplaces will be doing some social catch-up this year. And at some point, I expect to see the integrated retailers (my bet is on Nordstrom.com) and ecommerce pure plays dabbling in this area. Come on Amazon, what are you waiting for?

Lastly, there is so much potential to utilize social networks to enhance the online shopping experience – from trust, to referrals, to discovery – etc. I look forward to watching the evolution of this space in the coming months.

In the meantime, I’d love to hear if anyone has seen anything cool that I’ve missed!!