I have been looking for a good spatial data analysis package for a while now. Most statistic package offer some spatial dimensions but they are relatively limited. ArcGIS has a wide array of spatial statistics but it is often too obtuse to be useful in any particular case. Other packages cost serious coin (e.g., SpaceStat) and make it difficult to be made available for students.
GeoDa from UIUC, however, seems to solve these problems as it is focused in purpose, laden with features and free. Importantly (for me), it does quantile and standard deviation mapping something that can't easily be done with Golden Software's Surfer. It only runs on a Wintel machine (drat), but using the free Q and an XP license, one would be up and running fairly quickly with modest cost on a Mac.