The Star Trek Personality Test
The Star Trek Personality Test at startrek.about.com was rather inaccurate, but entertaining nonetheless. If you know your Myers-Briggs type already, here are direct links to your Star Trek character:
ESTJ|ESTP|ISTJ|ISTP
ESFJ|ESFP|ISFJ|ISFP
ENTJ|ENTP|INTJ|INTP
ENFJ|ENFP|INFJ|INFP
I disagreed with the characters chosen in some cases. Certain personality types are rare (1% of the population), so there may not be an appropriate regular character for them.