I recently read The Rust Programming Language. The whole language feels very cohesive. It has an official package repository located at crates.io. Although I am not a fan of centralized packaging solutions, the clear benefit of this system is its ease of use. Libraries can be added to a project by simply adding the name of that library to the project configuration file.
I thought that a great first project would be to implement the Secure Hash Standard (NIST FIPS 180-4), which includes the SHA-1 and SHA-2 (SHA-256, SHA-512, …). Yesterday I implemented SHA-1, and its repository is located here. I have not optimized it. This is quite obvious as hashing GNU Make, which is about a megabyte large, took multiple seconds. However, before I return to SHA-1, I might as well implement SHA-256 and SHA-512.