I just read a great post on “Work Awesome” last week that asked the question: “How do you pick your friends on social networks?“. I thought I’d share some of my insight into five key business networking hubs  that professionals need to keep synced with their business rolodex. Feel free to bookmark this post and share with your colleagues who wonder how to get the most from social networking sites from a business angle.

Every professional should approach the art of friending strategically and with greater seriousness like your career and reputation depends on it. And, trust me – it does. I think “People you may know” is a great place to start on all three key social networking sites but the webmail importer is a far more strategic way to approach “friending”:

1. LinkedIn: Without doubt, this should be the CENTER of your business networking universe as it contains the most accurate information mass resume / rolodex / conversation ecosystem you could find. 75 million professionals, millions of companies and tons of opportunities for professionals from finding jobs to collaborating on business. You want to make sure your LinkedIn network is an accurate reflection of your real world professional connections.

The easiest way to do that – find your business connections from your email. LinkedIn has a feature called webmail importer that makes it trivial to find and add your business contacts in your email client to LinkedIn. Fact is, most of them are likely to be on LinkedIn already. Also, all the remaining tips in this post will work more effectively ONLY if your LinkedIn graph is maintained accurately.

Once you’re done with that, try to check the “People You May Know” widget on the top right hand corner of your LinkedIn homepage on a daily basis and add 2 – 3 relevant business connections that are recommended. Click “See more” once every week, to do a more serious update and you’ll be surprised to see a faceted search module on the left that lets you zone in on the most valuable connections for you to add. Just adding folks from your current job alone is priceless!

Most importantly, make it a habit, to add folks you work on projects with on LinkedIn right away. To me it’s a daily ritual at the end of the day or week to add folks I’m newly working with on projects to LinkedIn. And, the best place to find them would be LinkedIn’s advanced search.

2. Microsoft Outlook / Xobni:

Pulling your  business rolodex (in this case – from LinkedIn) into your email client of choice is equally important, because it’s a great way to enhance the value of your email client. Your LinkedIn graph of connections and conversations can be pulled into Microsoft Outlook through LinkedIn’s Outlook Connector. Download it here.

As soon as LinkedIn and Outlook are connected, Outlook will start bringing in information about your LinkedIn network.  You should then start seeing profile photos and LinkedIn activity for any connection that e-mails you.

Xobni does the same through their plugin that works on Outlook and even in mobile – Blackberry. Unfortunately, it doesn’t work with the iPhone, but chances are greater that your company has provided you a Blackberry at work. And, I’m guessing you’re also stuck with Outlook.

I haven’t tried it, but TechCrunch claims that the difference between Xobni and MS Outlook connector seems to be that “it does email search a lot better than Outlook and can resolve different identities to the same person in your contacts list.” If interested, check it out here.

3. Google Contacts / Rapportive:

As a Google contacts user, I find myself increasingly syncing my gmail contacts to my iPhone and find it challenging that Google contacts doesn’t sync with constantly updated professional information on LinkedIn. Enter Rapportive, a browser extension, that pulls LinkedIn, Twitter and Facebook information of individuals from the gmail address. It’s like Xobni, but for Gmail.

4. Twitter:

I’ve shared this before, but sync your Twitter and LinkedIn accounts. Now, this allows you to do two things. One cross-post from LinkedIn to Twitter (harmless) and from Twitter to LinkedIn (careful, I’d only recommend bringing over the #in tweets).

Secondly, you can auto-create a constantly synced Twitter list of all your LinkedIn connections. Oh, yae! Read more about that here.

5. Facebook: Personally, I keep my social and business contacts separate. I love using Facebook to keep my friends and family up to date and there may be the one-off business peer who I know socially, but it’s the exception. That said, if you’re a consultant type who uses Facebook for everything I guess you could still try the same tactics I recommend above for LinkedIn. It’s your call, but beware.

Do location sites matter to professionals? I added this since Work Awesome mentioned Foursquare, but frankly sites like Foursquare don’t offer any value to professionals – today.

That said, I do see value in knowing the location of my business contacts. You can already see this on LinkedIn’s Tripit app (for e.g.). Feel free to leave a comment on how YOU sync your business contacts across multiple social networking sites?

Disclosure: I work at LinkedIn, blog here (subscribe) and tweet @mariosundar.