Tinkerplots is a really creative piece of software for middle school data analysis. Tinkerplots 2 has just been released.
The Tinkerplots developers are really, really smart about designing ways to get kids interacting with data much as they interact with square tiles when studying area. I wish they were 20% more clever about user interface design, but it’s a relatively minor quibble and they are saddled by certain features of Fathom, a more sophisticated educational data analysis software package upon which Tinkerplots depends.
For the record, I have no financial interest of any kind in this product. Its functionality is incorporated into several Connected Mathematics units and I do work for CMP, but on a salaried basis unrelated to sales or the publisher.