Echoing the dot-com boom a decade ago, a wave of Internet companies with lots of buzz but shaky business models went public this year. Here's how they've held up.

Demand Media

Ticker: DMD
IPO date: January 26
IPO price: $17
Now trading at: $8.06
Revenue for first 9 months of 2011: $240 million
Loss for first 9 months of 2011: $15 million

A solar power station in space measuring several kilometres in length may sound like something from a science fiction film, but the reality is that this idea could well be operational and supplying much of the worlds energy requirements within less than 20 years.

Space based solar power stations are not a new idea, in fact they have been researched since the 1970’s.

The acquisition of Motorola Mobility (NYSE:MMI) by Google (NASDAQ:GOOG) is one of the biggest M&A deals in the tech space for 2011. At or right before the closing of the deal, the $39 calls will be worth $1.00 (as Google is buying MMI for $40 a share) giving the call buyers a nice return of $.35 for the calls they bought for $.65.

Daily deals site Groupon priced its initial public offering at $20 a share late Thursday, the last step on a rocky journey to its debut.

The move values Groupon at $13 billion, and will net the company around $700 million of much-needed working capital.

Groupon will start trading Friday on the Nasdaq, under the ticker GRPN.