I have long been a fan of boxplots until Greg Johnson informed me
about violin plots (R package vioplot). However, now there seems to be
one better. Beanplots are similar to violin plots, but definitely show
more information, particularly when there are multiple subgroups.
Beanplots are available in the library "beanplots". More information
on them and some example code is available at:
http://www.jstatsoft.org/v28/c01.