Selecting a topic to write about doesn't have to be difficult. The resources above can help you avoid writing about a run-of-the-mill topic about which your professor may be tired of reading.
One approach is to take a general topic area and use this Topic Selection Checklist to help you walk through the steps of refining your topic selection.
Another approach is to browse websites that list current topics, such as the following sites. Remember - your syllabus will usually give you the specific requirements that your professor has for topic selection.
CQ Researcher - browse this excellent news source with the Issue Tracker feature - it will provide a list of over 200 possible topics, along with links to the issues of CQ Researcher covering those topics.
Public Policy Issues and Groups (Vanderbilt Univ.) - this website from Vanderbilt University is arranged in an alphabetic directory of 100 topical pages that feature extensive links to many of the most important social issues and public policy questions of the day.
Wikipedia - Although not usually an acceptable university "source", because of its open editing policy, Wikipedia is a great source for browsing and brainstorming topics. Use this Lists portal page to navigate through the many lists in Wikipedia to find a interesting topic.
Try selecting a topic about which your professor hasn't read, a fresh topic could cause a mild halo effect which could help your paper appear even better. After you've explored some topics, if you're still stuck on how to get started you can get help at the Reference Desk or at the Learning Center.