I think the key is to have a third party test you. Ideally this third party has created a profile of you.

The above is better then selecting test yourself. I think you could do better though.

My solution would be to give an interactive test that gives you a harder or easier questions based off of how you answer the questions. I would incorporate this with a profile so that when you come back the next day it knows what level of questions to give you. Ideally you could test several types of IQ with few questions.

The tests-questions-games like the above posts would be designed to be fun.

At the end the test would tell you how you preformed compared to other times.