It would be great to see some improvements added to MySensors lib. Like a good message Queue and stuff like that. Ways to get more state out of the lib so you can provide a bit more user feedback. Right now I have some of those in my own lib. When I have time I'll post some on this forum. So others might benefit.
But I'm currently hooked up to modular synths. Learning a lot of analog technology. Which broadens my Arduino horizon.