There are many intelligence test all over the internet. Quizzes and surveys that after tell you how you score. They usually are based of what the average score in general is.
Here is a link to two such test. Try it and let us know how smart you are ;)
http://intelligence-test.net/part1/
http://www.begent.org/intelquiz.htm

How much are these intelligent test accurate. What are they based of. Do they have an similarities to an IQ test.
Most intelligent test that are giving on line aren't really accurate. The questions are often not thought out and the answers can be easily skewed. If they are basing your score off the average person, you don't know for sure that  they are not looking up the answers or having help.
Most of the test do use the IQ test as the base of their testing. The IQ is the most standard test so of course they look to it for guidance.
The test online are just for fun and don't really have anything accurate about them. So if you took the quiz and you got a low score- have no fear, they aren't always accurate. If you got a high score- the test might be accurate so you know it must prove that you are as smart as you know you are. :)