Groupon for one, please.

For $6 billion, this site would be sold in a nanosecond (possibly with a kidney included), but Groupon looked the multi-billion dollar offer in the face and decided to walk away. Chicago Breaking Business {via TechCrunch} reports that two sources close to the deal have confirmed that Groupon has decided to stay independent, possibly in advance of a IPO filing, though a decision on that won’t come until 2011.

How could anyone possibly walk away from $6 billion? According to Kara Swisher at AllThingsD, the $500 million annual revenues that everyone’s been tossing around (including us) are actually closer to $2 billion. While that figure doesn’t take into consideration what Groupon pays out to merchants, most estimates have Groupon taking a 50% cut of each deal that passes through its site, which means the company could be seeing $1 billion from the deals that pass through their system. Considering this is still in a span of just 2 years, heading for an IPO might make more sense. With their own focus on acquisitions – of both smaller companies outside the US and new customers – Groupon hasn’t been resting on their first to market status to grow, and it’s obviously working out amazingly well. If they hit $3 billion in revenue next year, an IPO could easily see the company valued at much more than the $6 billion Google offered.

Only time will tell if this is the right move: when Facebook turned down a $2 billion offer from Yahoo!, many observers who’d seen Friendster’s rise and fall thought it was a risky move. Today the company is valued somewhere close to $50 billion and it looks like the right bet. As successful as they’ve been, it’s still impossible to know for sure if Facebook will continue to hold the number one social network spot that MySpace once held, and officially conceded. For Groupon, the loudest criticisms of their multi-billion dollar valuation have been over the fact that the model can be easily duplicated, and that there’s not much that would keep someone loyal to Groupon exclusively.

While they may not be the only daily deal site that customers keep up with, Groupon is quickly turning the space into a winner take most market and sometimes that’s enough to build a defensible business on. The momentum Groupon has going for them at the moment may be a challenge to sustain, but it would be an even tougher battle for competing companies to overtake them.

Meanwhile, this puts Google back to square one. Amazon recently offered competitor LivingSocial $175 million, BuyWithMe is the next largest competitor, but not in enough cities for Google to spend money on an acquisition rather than trying to build its own product and sales force. Will we see Google Deals/Goopons making their way into local listings? Google branded products have been hit (Maps, Earthview, Gmail, News) and miss (Video, Buzz, Wave, Froogle, Base) so it’s difficult to say how they’ll move forward, but we can’t see them walking away from the  daily deal model after what was on the table.

These coupon 2.0 sites all operate on a very similar premise: the “tipping point.” They understand that, in these recessionary times, consumers aren’t just looking for deals – they’re looking for killer savings. They also understand that companies aren’t going to slash their prices unless they’re guaranteed a slew of customers to make it worth their while. The result? Online shopping that harnesses the power of collective buying to get you the best possible price around.

Here’s how it works. These hyper-localized sites negotiate an amazing deal with a restaurant, salon, dance studio, driving range, etc., near you. For a limited time frame, they offer the deal on their site. As soon as enough people commit to buy – and the “tipping point” is reached – the deal is on. And you just got a coupon for 50, 60, even 90% off that you can redeem at your leisure.

Sound good? Well, we won’t leave you with all that new found knowledge without telling you how to put it to good use! We’ve found the best of the collective buying sites and ranked the top 5 according to the number of locations, time frame, average savings, and (very scientifically) general coolness factor.

#5: CoupMe

Locations	Time for Deal	Savings	Coolness

It may not be the sexiest site, but CoupMe does have one feature that sets it completely apart. Every month, 5% of its profits go to a different charity. So while CoupMe is on par with your typical collective buying site (50% savings, a 24 hour time frame) and is only based in Boston, this is the only site to go to if you want to make a purchase for a cause.

#4: LivingSocial Deals

Locations	Time for Deal	Savings	Coolness

Available in Boston, New York, and Washington D.C., Living Social is a site for the kind of person who has over 400 Facebook friends (come on, can you really know that many people? really?). Brought to you from the people who created LivingSocial, a site that lets you rank, review, and share your favorite finds with your friends, LivingSocial Deals hopes to harness the power of their social network to sustain their deals. While the savings are above-average, hovering at about 55% off, the real steal is the free deal you get when three of your friends buy!

#3: BuyWithMe

Locations	Time for Deal	Savings	Coolness

If you’re the kind shopper who finds yourself getting heart palpitations at the strangely pressuring prospect of a 24 hour time frame, then check out BuyWithMe. With deals that can last up to a week, BuyWithMe gives leisurely (read: horribly indecisive) shoppers in Boston, San Diego, and Washington D.C. the time to ponder if this deal’s truly right for them.

#2: My Daily Thread

Locations	Time for Deal	Savings	Coolness

What MyDailyThread lacks in number of locations, it makes up for in awesome savings and cool editorial content. With its Atlanta-based companies carefully chosen and featured with in-depth reviews from the MyDailyThread writers,  you get deals that are only to places that truly embrace “the creative lifestyle.” Plus, with an average savings of about 60% off (the highest average we came across), you know that you’re guaranteed to have a great time – for a whole lot less.

#1: Groupon

Locations	Time for Deal	Savings	Coolness

Available in a whopping 35 cities, chances are that a Groupon is available to use at a store near you. Groupon was the original collective buying site and has grown exponentially since it started in late 2008. As a result, they’re getting better and better companies to spotlight with deals at better and better prices. With a cool, easy-to-use site and above average savings, Groupon is the site to check daily for the best and most varied deals across the country.

Read our in depth review of Groupon, with feedback from business owners and CEO Andrew Mason’s most memorable deals.