There are a few R packages I just wrote to have examples for my books, but I now think they might be generally useful. I just haven’t taken them to the point where they are. I know I am lazy enough to just leave them as they are, but if I could get collaborators who would like to work on them with me, I think we can make something out of them.
There is the bindr package that makes it just a tad easier to work with functions that return more than a single value.
Then there is the dfdr package that computes the derivative of a function with a bit of meta programming, that I can see greatly helping in numerical optimisation.
And, of course, there is the ralgo package I am working on right now for efficient data structures in R; I implement data structures in it as I write my next R book.
If anyone out there would like to be involved in a little bit of R programming with me, I would love to collaborate.