S3 Infrastructure for Regular and Irregular Time Series (Z’s Ordered Observations) (zoo)
An S3 class with methods for totally ordered indexed observations. It is particularly aimed at irregular time series of numeric vectors/matrices and factors. zoo’s key design goals are independence of a particular index/date/time class and consistency with ts and base R by providing methods to extend standard generics.

Quantitative Financial Modelling Framework (quantmod)
Specify, build, trade, and analyse quantitative financial trading strategies.

Database Interface and MySQL Driver for R (RMySQL)
Implements DBI-compliant Interface to MySQL and MariaDB Databases.