PhET simulations-- curve fitting

A colleague just texted me to ask "What is that place with the great physics demonstrations?" She was asking about the Univeristy of Colorado at Boulder's PhET simulations-- pages full of virtual experiments you and your students can manipulate. (Chris Dede's virtual environments for everyone to use!)

After I reminded her of the site, I went and poked around there as I hadn't used any since last fall. I am not sure if this one is new or not, but the curve fitting simulation is really useful. I have seen several other similar interactives, but this one seems to be far easier to use then the others and the ability to drag error bars adds an interesting feature.