All the talk is of an Internet bubble - and there is even talk of a bubble in discussion groups talking about the bubble. But could Groupon's big staff really be the thing that makes it worth the money?

According to filings with the US Security and Exchange Commission, the sum it hopes  to raise  with its IPO is a much more modest $750 million.

But just as LinkedIn's estimated value before its IPO last month was just $3.3 billion - and the value of the shares actually on offer was just $700 million on Day One - the company finished being worth $10 billion in 48 hours as punters rushed in.

So that's why the hopes are so high for Groupon, although it actually lost $389.6 million in 2010.  Can Groupon really be worth up to  $20 billion? On the plus side, between 2009 and 2010, its revenues increased by 2,241 percent, to $713 million and that figure could quadruple this year.  Revenue of $646 million in coupon sales was reported in  the first quarter, although overall Groupon lost $117million. Despite last year's loss, "revenue is growing at a steady clip, however, well up from the year-prior period," said  AdAge on an optimistic note.  One of the question marks over Groupon is that it is a relatively easy idea to copy - and plenty  of people have been doing just that.  Apart from standalone businesses ( such as Living Social)  newspapers and biggies like Google, Amazon and Facebook have piled in with  their own daily deals, offering  cut-rate specials  on behalf of local merchants. But national deals are also working for Groupon: the company  turned $11 million in a single day selling 400,000 coupons for the Gap. Three years ago the category barely existed, says AdAge. Now it is estimated the deals market will reach $3.9 billion in the US by 2015. And it's not just the US. From its Chicago base, Groupon has expanded worldwide, sending email deals to 83 million subscribers in 43 countries including the UK. So what makes Groupon different from the rest in the high tech business? Oddly it's that old-fashioned thing, a large and enthusiastic work force.  Facebook had fewer than 100 employees at its two-year mark and today still has only 2,000. At 30 months old, Groupon has more than 7,000 employees,  up from more than 5,000 in just March.  So could the visiting sales person, calling on local businesses, make Groupon a much better bet than the rest - and worth that $20 billion? Ask us in a year's time.