By Dana Oshiro, NetShelter.

After watching The Social Network and Mark Zuckerberg's alleged fascination with getting into Harvard's Porcellian Club, I'm beginning to understand the value of exclusivity. You want friends that are cool, that are more signal than noise, and that don't bring shady stoners over when they're couch surfing at your place.

Ironically, for all Zuck's love of privileged privacy, he and Facebook encroached on my location-based privacy early this year by making my city searchable to random grade school friends.

I've learned two lessons. The first is to refuse my home to those I haven't seen in 20 years, and the second is that location-based services require tighter user control.

Marco creators Josh Rooke-Ley and Tarikh Korula aim to solve that.

Marco is an app that lets you send an exact location via text message to the user of your choice and the receiving party doesn't need to download or use the app. Anyone with a Webkit browser that supports location services (iPhone, Droid, Pre, WinMo or Blackberry) can view the Marco SMS and be directed to a mobile site to reply within a 30 minute period.

If they play along you'll see their response in real-time on a shared map with directions on how to meet them. If they ignore you, then your session (and possibly friendship) come to a close. It's all very simple. There are no public feeds and no awkward confrontations.

While Foursquare and Gowalla are great for promoting open events, you certainly don't want people picking up a swarm badge at an AA meeting. As for Facebook's Places, the reality is that if you've been too lenient in accepting friends, you're either afraid you'll prompt a flashmob or you'll miss updates in a noisy wall feed.

Marco's value is in user privacy control.

Similar to EchoEcho, the beauty of Marco is that your information is not publicly shared. In addition and as an added layer of privacy, because Marco users don't create an account, the company doesn't store location information on its servers after a session expires. What a concept! Explicit privacy controls built directly into the user experience!

Far be it for me to choose this as the winner in the war of the location-based apps. These guys are barely out of the gates, Marco only works on a one-on-one basis, and session initiators need to download an iPhone app.

But the experience is certainly more conducive to those of us with privacy concerns. Plus there are plans to launch multi-party SMS alerts and a Droid application in the not so distant future.

If you're like me and you just want an app that will connect you with your inner circle, download Marco for free from iTunes. If you want more info or you want to check on the Droid release visit usemarco.com.

Dana Oshiro | netshelter.net | readwriteweb.com | villagerswithpitchforks.com | @suzyperplexus

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