1) The sandbox I mentioned in this thread would be for news articles (not user written blog-esque articles). There would be some basic filtering at the level of the editor so that people can keep up (my main complaint with digg is there are just too damn many articles put in the sandbox). Aside from those two differences the decision on what to put on the mainpage would be a lot like kuro5hin.
2) "genetic mutations" in mod selection. Every so often a person would be given mod access at random. This would be used to prevent inbred points of view and to provide seed capital for new points of view. Perhaps as a steady state or in a punctuated equilibrium fashion.
3) No hidden slashvertisements. One unobtrusive text ad to the side of every article. If google can do it then so can I
Once per month there would be a user freeforall in the sandbox where what is submitted are not articles but suggestions for improvement. The mods would then vote on the improvements and the top one would be implemented as funds and availability of resources allow.