Does anyone know about free linux servers that can be used to practice KDB+/q? I have cygwin installed on my machine, but am not able to extract the free KDB+ version onto it. Please suggest.

If you want the linux version use a VM to run linux and install to that. There are also Windows versions available. My guess, however, is that you are going to be hard pressed to find a cluster of machines available for free to host your data processing; most services of that sort (that are non-academic) require a registration and fee for use.

Thanks a lot L7Sqr..i've installed the same :)