First write down some topics that you are interested in, know a lot about or are happy to research.
Use the Google Adword tool and type in some key phrases based on the topics. You will quickly find out which key words are well researched but don't have to much competition. Go for a key word phrase of less than 20,000 hits per month and that doesn't have to much competition (the tool shows you this).
Type the keyword phrases into Google and see what type of advertisements come up. You will then have an idea of the type of advertising that you will attract.
Ofcourse make sure you write useful information as a first step. If you are looking to make money, then as a second step write content that leads into the advertisements.
Write some hubs based on the key word phrases and the advertising.
The number of people who click on your advertisements will be dependant on the number of people who click on your hub, so you need to promote it. Use some social bookmarking sites, relevant forums that allow it, and also ping your sites.
After you do this you should have some revenue.
Hope the above helps. As siimeonvisser wrote, and I agree, I won't provide any specific details on the type of niche or the like!
Best of luck for 2011