Free Java Programmer's Test
I stumbled on the site http://www.betterprogrammer.com today and found that it offers an open book programming test meaning you can use all reference (like one can do at work) but complete 5 programming exercises pertaining to use of core Java language for writing algorithms. It requires lots of Java collections framework usage and writing some recursion algorithms, writing tree traversal code, calculating prime numbers and stuff like that. The time limit is not very strict and it even allows you to take a break and then continue with the test. In the end you are given a free certificate based on percentile (which it states will keep changing - read may improve - with time, as more people take this free test). The questions were good quality and if you have some free time and like to write code then its quite a good avenue to spend some time on.
My certificate is here: http://www.betterprogrammer.com/certificate/BP1Q9GB5
They claim to maintain this certificate for you in their database and that you can retake the tests to improve (not sure if the questions remain the same - if they dont change then thats a bummer) but anyway take it once and you will love it. If you have taken this test already then feel free to leave your comments on how you liked it or discuss the questions you liked/found interesting.