Currently I'm working on file compression program in Rust. Nothing too fancy, it just use common algorithms (LZ77, LZ78, etc.)
The only difference here is that the program will switch on the fly between different algorithms depending on which one that can compress file smaller.
It can compress 1 GB file (enwik9) down to around 230 MB. Pretty good I guess for something that I worked in my spare time.
I'm not publishing it yet, since I'm still experimenting with it a lot.