For R-related packages, go to http://r-project.org first. Click on CRAN and choose a mirror location, then click Packages on the left-hand side. We can see two lists, as shown here:
On February 22, 2018, there are 12,173 R packages available. The first list contains all available packages sorted by their publication dates (that is, the dates they updated, or published if they were never updated). The second list is sorted by their names. If we just want to find relevant packages, either list will be fine. For example, for the first list, here is a snapshot of a few lines:
The first column shows when the packages were last updated, or published if no updates were available. The second column shows the names of the packages, while the last column offers a short description of the usage for each package. We can use keywords to find the packages we want...