PSAboot is an R package to assist with bootstrapping propensity score methods. I gave a talk today at the useR! 2014 Conference. The slides can be downloaded from the PSAboot Github page or directly here. The package is described at jason.bryer.org/PSAboot and maintained on Github at github.com/jbryer/PSAboot/.
Also, version 1.1 of the package was just released to CRAN.