Hay Dan can you add visible gravity to universe sandbox 2 and can you make it 3D with color cuz i think it would look realy cool in universe sandbox 2
I found a topic about this for universe sandbox that was created by someone named Hallowed Error
http://universesandbox.com/forum/index.php?topic=87.0
That is actually something we implemented about... 2 years ago? but then removed again because of various small issues. The distorted 2d plane visualization obviously have issues with space being 3d and the offset of the 2d plane therefore not really making sense, but this can be done in 3d as well as
http://orbismediologicus.files.wordpress.com/2009/12/spacetimelu31.jpgwhich makes a little more sense.
The plan was to implement both (we only did the 2d distorted plane) but it has been put on the back burner for the time being. If you really want it, you can pester us about it some more and perhaps move it up the todo list ;-)