Take a look at https://codegolf.meta.stackexchange.com/a/1067/9498 and the discussion here: How can new users use the Sandbox?
In my question How can new users use the Sandbox? , I question whether the sandbox should be moved to the main site. Jan Dvorak convinced me that it might be a good idea. Please vote here (on the accepted answer) on whether it should or should not be moved to the main site. Also, feel free to post any concerns, etc that should be addressed concerning this.
The answer is only accepted to make it easier to find.
Post any suggestions for what this sandbox should be like as an answer and people can vote on these too.