I'm no math whiz, but I dig probability and statistics. I've been using R to do some data analysis at work and I'm reminded of what a nice tool it is. I wrote a tutorial about graphing in R on freshmeat.net, which describes a few of its graphing capabilities. It really only scratches the surface. If you want a more in-depth introduction, the must-have Christmas stocking stuffer is Harald Baayen's forthcoming book Analyzing Linguistic Data: A Practical Introduction to Statistics using R. For a good illustration of the fun you can have with R, check out my Powerset pal Brendan O'Connor's analysis of country names (with graphs produced in R). It got a shout-out on Language Log!