WiFi client filtering
One thing I have a few customers and friends using on their current systems is client filtering.
Devices like a Grandstream GWN7610, a Draytek Router/AP, even a WRT54GL with DD-WRT on it - they allow you to filter allowed WiFi clients by MAC address. If you're not on the list, you can't connect.
I'd love to see a system like this implemented here - it's incredibly useful in places where people prefer to be able to plug anything in physically but lock down the WiFi network.