Popular MBA specializations or MBA specializations in demand. (Demand for Finance has declined a bit & demand for Entrepreneurship & others like Int Bus., Proj. Mgmt. has increased)

This is not a comprehensive list. And there is no specific answer to this question. Popularity of MBA specializations vary from time to time. There is no right or wrong choice. It is up to the individual. However, it has been found that the demand for MBA Finance has decreased by a little and demand for other fields like Entrepreneurship has increased.
As per one survey conducted,  these were the Top 5 popular choices (totals do not add upto 100%):

• General Management (52% of respondents found it important),
• Strategy / Consulting (50%)
• International Management / Business (47%)
• Finance (38%)
• Entrepreneurship (30%)

More excerpts from the link above:
“Governments have come to the view – rightly or wrongly – that their influence on their economies is greatly weakened in a globalizing world and now put great emphasis on business start ups and entrepreneurship to generate jobs and growth. Not surprising therefore that entrepreneurship has a higher profile in business schools.” "There has been a shift in the way business schools see their role in society. business schools for a time seemed to be content at being good at providing management education. Increasingly they seem to be thinking that their role in society is to make the world a better place. We increasingly see graduates interested in social entrepreneurship.” 

After the financial crash [at the end of the last decade] the finance sector was offering fewer career opportunities to MBA students and this is likely to be the case for some time as banks and other institutions come under greater regulatory control.” As a result of reportedly fewer jobs available in finance industries, MBA applicants have chosen to pursue careers involving entrepreneurship as a more realistic option.

“There have been fewer opportunities for MBA graduates to move into have the financial services sector recently”. “This has meant that students have looked at other sectors and have chosen electives such as entrepreneurship or project management which may fit their career aspirations, perhaps for some, better than Corporate Finance.”