A Modern and Flexible Web Client for R (curl)
The curl() and curl_download() functions provide highly configurable drop-in replacements for base url() and download.file() with better performance, support for encryption (https://, ftps://), ‘gzip’ compression, authentication, and other ‘libcurl’ goodies. The core of the package implements a framework for performing fully customized requests where data can be processed either in memory, on disk, or streaming via the callback or connection interfaces. Some knowledge of ‘libcurl’ is recommended; for a more-user-friendly web client see the ‘httr’ package which builds on this package with HTTP specific tools and logic.
The curl package: a modern R interface to libcurl

Environments Behaving (Almost) as Lists (listenv)
List Environments are environments that can be indexed similarly to lists, e.g. ‘x <- listenv(); x[[2]] <- ‘b’; names(x)[2] <- ‘B’; print(x$B)’.

Methods for Estimating Dynamic Treatment Regimes (DynTxRegime)
A comprehensive toolkit for estimating Dynamic Treatment Regimes. Available methods include Interactive Q-Learning, Q-Learning, and value-search methods based on Augmented Inverse Probability Weighted estimators and Inverse Probability Weighted estimators.