It would be really interesting if you'd like to implement some quantum chemistry! Rick Muller (of PyQuante fame) has implemented a port to Julia, but I think there's a lot of room to use more language features.

https://github.com/rpmuller/pyquante2/tree/master/julia

Let me know if you do want to do some quantum chemistry coding. It would be good for my soul to revisit some of my PhD roots...