You think that one is cool, go check out "~?" in IPMI "sol activate". From there you can deliver a serial break to the kernel, which then gets you to a third rarely seen menu from the kernel's console, which allows you to do kernel debugging of various sorts.

I use it when I need to crash a kernel on purpose to test kdump over the network.

You can also send commands to the simulated console of a VM under libvirt with "virsh connect". But I don't think you can send a break to the kernel with that.