Scott Kildall made excellent tutorial where he described in detail how you can make "data crystal" 3d printable objects to visualize or present large data sets. Data sets can be anything, he used data sets from OpenData.
Detailed guide is at:
http://www.instructables.com/id/Data-Crystals-3D-Data-Visualizations-from-Open-Dat/?ALLSTEPS
Here is video of algorithmic data clustering to produce the model:
Here are more visualization projects where 3d printing is used to present 3d objects from data:
Video tutorials on how to make 3d models from CT data for medical applications:
http://diy3dprinting.blogspot.com/2014/02/how-to-create-model-for-3d-printing.html
How to hide data in 3d printed objetc shape:
http://diy3dprinting.blogspot.com/2014/01/object-steganography-method-to-hide.html
Printing molecules :
http://diy3dprinting.blogspot.com/2013/07/how-to-3d-print-models-of-molecules.html
Update (29.9.2014.):
Scott has new tutorials on how to make 3d models of sewer and water systems from processed data:
http://diy3dprinting.blogspot.com/2014/09/how-to-make-printable-3d-models-form.html