My third-year project was an IP stack for RMoX. In fact, I wrote it as a userspace process on Linux talking to the Linux IP stack using SLIP, and Fred later ported it to RMoX.
Obviously, it'd be useful to have a proper IP stack. occamnet as it currently stands has a few good features (I've done all the tedious stuff, like coming up with headers and writing code to do IP checksums properly) and a lot of bad ones (no TCP, at least one obscure bug in UDP, incomplete ICMP, dubious user API). Beating this into shape, and writing some network card drivers for RMoX so that it's actually useful, will be a useful project.
One of my specific plans is to make use of the new nested mobiles support to have a less clumsy representation of IP packets.
(And this is exactly what I did in the first year of my PhD.)