I came across a very nice online tool to study the 42 Project Management Processes from the PMBOK Guide 4th Edition. You can review the processes by Process Groups, Knowledge Areas, Process Number, or Process Name. You can also study the Inputs, Outputs, Tools and Techniques.
A really good feature about this tool is that given an input or an output, you can easily see the list of all the processes where that input is used or the output is coming from. Similarly, for Tools and Techniques, you can see the list of all the processes where a particular Tool or Technique is used.
If you are preparing for the PMP or CAPM exam, you will surely find this tool useful: