A while ago Ishak Suryo L posted a very useful tool that allows you to stack different geometry on top of each other along the Z axis:
http://vimeo.com/126746868
I’ve developed my own variation of this tool (download it here) that also works along the X or Y axis. In addition if you don’t provide a “target” node to stack, it clones the base mesh along the given axis.
http://www.youtube.com/watch?v=KIj6MzRB2P4
To stay abreast of new and cool MCG tools like these be sure you join the MCG Facebook group.
In other news if you are going to be at Siggraph come on by to the Autodesk Vision Series talk on Procedural Content Creation by Martin Coven and myself which will be on Tuesday, 11 August at 4:30 PM Los Angeles Convention Center, Room 408A.
I hope to see you there!