I've still got a foot of snow on the ground, so there are limits to what I can do.
I did just set up and test a surplus lab-grade incubator for precision temperature-control to encourage germination. I'm planning to set up lights in my cold basement for
cold-stressing a batch of tomato seedlings, as well as selecting for micros out of a F2 population I've got.
Experimentally, I've got some of last years carrots growing on the windowsill… hoping I'll be able to get seed out of them early enough to be of use this year.
The last item of "zone-pushing" I've got is a couple mature peppers that I've overwintered in an insulated light-pod. Night temperatures in my basement have pushed them into dormancy, but they are ready to wake up as soon as it gets a little warmer. One is a super-hot Datil-type. The other is a squat, purple bell that sprouted and grew at temperatures which killed all 78 of the other seeds I planted early last spring. (I will be testing seeds from it for cold-start ability under lights, as well.)