A useful feature would be to stack elements horizontally or vertically, if they share the same x and y values.
Here's the file for it: https://gist.github.com/1217836
I'm going to put this off until 1.0. Too much in this version already.
This sounds like a great feature, but unfortunately we don't currently have the development bandwidth to support it. If you'd like to submit a pull request that implements this feature, please follow the instructions in the development vignette.