With the number of collective years of experience on this forum, I'd imagine that many questions can be answered "from the hip," as it were--without having to actually code or test a solution. But for those intriguing problems where only running the code will do, what's your preferred setup?
For example, I spend most of my time lurking in JSP/Servlet land, so I have Eclipse set up with a local "test" project. I'm setting up a generic servlet, filter, and JSP that I can edit based on the specific configuration in question.
I prefer when the person with a question provides a sufficient amount of information so that I don't need to run anything. Usually with the error message and code snippets, there isn't a need to actually run it.