Personality Tests - worthwhile or worthless?

Since starting to interview at BlogFrog, I have started to think a lot about personalities and what makes someone a great performer.  I've learned a lot so far, and I look forward to posting even more after the process is over.

One fascinating (and not exactly scientific) thing is the measure of someone's personality.  One popular test is is the Myer-Briggs personality test (free tests are available all over the internet).

This test divides your personailty traits into four dichotomies:

• Introverted vs. Extroverted - This one is pretty self-explanatory and can be found out by answering the simple question - "Does speaking in a crowd get you amped up, or does it suck the life out of you?"
• Sensing vs. Intuition -  This is how new information is understood.  If you prefer sensing, you prefer information that is tangible, than can be understood by your 5 senses.  If you prefer intuition, you prefer information that is more abstract, like something that might come from your uncouncious mind.
• Thinking vs. Feeling - This is how you make rational decisions.  If you prefer feeling you like to get inside the decision and empathize with everyone involved.  If you prefer thinking you tend to detach from decisions and look at them very logically.  
• Judgement vs. Perception - This last trait kind of effects how you use the previous 3 traits.  Judging types prefer to have matters settled where perception types like to keep things open.  

I took a free test and scored a ENFJ.  Supposedly I'm an extroverted person who uses their intuition, trusts their feelings, and likes to have things settled.  Also (even more supposedly) I am in good company of other notable ENFJ's such as Barrack Obama, Ronald Reagen, and even David, biblical king of Israel.

I don't agree withe the "N" part and the "F" part.  I like to think of myself as a very logical person who makes rational decisions based on tangible information.  But the internet says otherwise, and when has the internet ever been wrong!  ;)

I think these tests are fun, but not very accurate and not extremely useful in deciding whether you will get along with someone or what type of performer they will be.