4 packages on CRAN
Build regression models using the techniques in Friedman's papers "Fast MARS" and "Multivariate Adaptive Regression Splines" <doi:10.1214/aos/1176347963>. (The term "MARS" is trademarked and thus not used in the name of the package.)
Plot model surfaces for a wide variety of models using partial dependence plots and other techniques. Also plot model residuals and other information on the model.
Plot principal component histograms around a bivariate scatter plot.
Plot 'rpart' models. Extends plot.rpart() and text.rpart() in the 'rpart' package.