There are many different personality and behavior assessment tools. The Myers-Briggs Type Indicator and DISC assessment are two of the most popular. Managers use them to understand their employees better. Individuals use them to understand themselves better. The idea is you learn about personality traits and tendencies so that you can be smarter about matching those tendencies with situations which play to your strengths. In other words, these assessments tend to treat revealed tendencies as innate and therefore permanent.
One reason I've held off taking such a test is that I am intuitively skeptical of how effective any survey or test can be at accurately capturing the nuances of a person. Also, I've seen these tests be overinterrepted by managers. For example, manager adminsters a test to subordinate, the test suggests subordinate avoids exerting authority and is introverted, manager concludes he's not fit to be a leader, and the subordiate defers to the test and shelves any leadership aspiration. These broader concerns aside, I do think that if one treats personality test results with appropriate distance, they can be a useful check on intuitions and a good starting point for a conversation.
Yesterday I took the Predicative Index test. Frederic Lucas-Conwell studied all the various tests for his PhD and now administers and consults around the Predictive Index, which he believes is the best. He was kind enough to do my test for free. It is remarkably short — it only takes about 10 minutes to complete, as you check off adjectives that describe how you believe others expect you to act and then adjectives that you think really describe who you are. After entering my results into a computer, Frederic displayed the following three charts. They're meaningless unless you know how to interpret this particular test.
Below the fold is the automated written report that accompanies my results (ie, "Ben" is plugged in a blank space for a pre-written report for my type). I think it underplays my introverted streak and underplays my interest in details and precision. Otherwise it emphasizes pretty typical entrepreneur traits. Note it focuses solely on professional and management issues, no "personal" situations or attitudes.