Seventy-five million people signed up for a Twitter account by the end of 2009, a new study reports, though only 17 percent of them sent even a single Tweet in

December, an all-time low for the micro-blogging service. Read more

James Cameron broke his own record Tuesday. With a $1.86 billion haul, Avatar passed Titanic to become the highest grossing movie of all time at the box office worldwide.

It’s a remarkable achievement. But before every Hollywood studio exec decides that all future movies must be in 3-D and feature blue aliens, it's worth getting a little perspective on the film.

Avatar has the advantage of showing in 3-D (which usually commands an average $3 extra per ticket) and coming out at a time wheneven 2-D movie tickets are more expensive than ever. According to the National Association of Theater Owners, the average ticket price in 2008 was $7.18, up 56% from prices in 1997 when Titanic was in theaters.

A look at domestic grosses adjusted for inflation shows a more realistic view of Avatar’s performance.

In the U.S., Avatar has grossed $555 million, making it the second highest grossing domestic (as opposed to worldwide) film of all time. Titanic is temporarily still in the lead here with $600.8 million.

But a chart adjusting for ticket price inflation on the Web site Box Office Mojo ranks Avatar as the 26th highest grossing film in the U.S. of all time. Gone With The Wind tops this list with a $1.5 billion adjusted gross in the U.S., while Star Wars ranks second with $1.3 billion.

Cameron’s Titanic ranks sixth (just behind The Ten Commandments) with an adjusted $943 million take in the U.S.

With no film on the near horizon poised to challenge Avatar’s dominance, the film is sure to continue to mint money. But it’s got a way to go to catch up with a classic like Gone With The Wind.

How do you measure ROI in social media? Can it be done? Is it worth doing? This interesting Forrester Research blog takes a closer look and asks some searching questions about companies who choose not to invest in social media. Read more

This article on Forbes.com is about getting response from online display ads and has some very useful tips and good examples of how you can feed consumers information in rich media display ads. The secret - don't take them away from the site they are on and what they want to be doing! As this display ad example from Amex shows.