You might want to check out Jon Jagger's fantastic Cyber-Dojo.
It's a web based integrated environment designed for doing deliberate practice of Test Driven Development and learning about team dynamics. It has lots of small programming tasks (kata's) and supports a range of languages, from Python and Ruby to Java and C++.
Unlike IDE's designed for productivity, there is no code-completion, syntax highlighting or auto-refactoring, so you get to see what your interviewee can do without these.
The best thing is, after doing a kata you can then go back and look at the red/green progression (or maybe not if they don't do TDD *8') of each of kata. Every compile/test commits the changes to a git repository along with the results of the test.
I think using this for interview coding tests could tell you a lot about not only a candidates ability to solve a problem, but also their approach to problem solving and the process they use when not constrained by external factors, just select a kata appropriate to the time you want the candidate spend on it.
If you want your own CyberDojo server, the whole project can be found at github and there is even a Turnkey Linux appliance virtual machine linked from there, which means that assuming you already have VMware player or VirtualBox installed, you can be up and running within a few minutes of downloading the appliance!