I'm a technology expert and enthusiast, so to me, almost all technology areas are good ideas!
Certain career websites usually conduct annual surveys on which careers are the 'hottest' and which command the highest salaries. But, my advice to you is to do some research about the different areas of technology. Find someone who works in the field and set up an informational interview with them.
It's generally not a good idea to start a business on a topic that you might not know anything about. So if you find an area of technology that you'd like to work in, try to get an internship or shadow someone in that position to make sure it's what you really want to do.
Once you're sure of that, get a job in that area. Don't be afraid to start with an entry level position so that you can fully understand that part of the industry. Then, after you've seen how things work as an employee, think about stretching out into a business of your own.
It might sound like a lot of work but it's a smarter way to make sure that when you do start your company it stays around for a long time.
Good luck!
Lena West is the CEO and Chief Strategist of
xynoMedia Technology , a New York-based firm that helps high-growth companies leverage the power of social media, blogs, podcasts and online communities.