I've never heard of  accessible  online IQ tests, but at least in the Uk some verified IQ tests developed for Vi kids  are usable.

When I  was 7, my mum was  attempting to persuade the local authority that  the  couple of hours of teaching assistant  time I got a week was having adverse affects on my learning ability.  They stated I was average, however my mum was fairly convinced I wasn't performing to the best of my ability, so ended up taking me to a learning institute to have a fairly high ranking educational psychologist perform a Vi specific IQ test.

Needless to say my mum was correct.

That being said, to be honest there is the problem that there are drastically different forms of intelligence and application, and emotional wellbeing an energy can have a huge affect on what you do, aside from the fact that getting a great IQ score just proves your good at taking IQ tests.

I  technically have a higher IQ than my brother, but he has a  problem solving ability that I don't, and is an international standard chess player. Similarly as I've said before my spacial comprehention is particularly lacking.

I have also noticed a tendency among certain people to hold IQ as some sort of great standard, indeed I was very disappointed as a teenager that when I phoned mensa in a desperate effort to find someone to talk to who was vaguely my age and had a brain, they didn't actually do  anything other than sit around and feel smug  about themselves.

So, unless you want it to prove some sort of practical point in an arguement I'm not really convinced of why an IQ test would be necessary.