Garage Door opener IOT – found that Chamberlain has a device that works pretty well, but leaves a little to be desired. Onion/relay seems like a good possibility.
Home thermostat controller – Raspberry Pi or Atmel with Wifi
Home sprinkler-system controller – Pi / Atmel+Wifi / Onion
Home security – cameras, motion, opening, control, notification
Get low-cost cameras working with Pi/Onion
Install commercial camera system
View/status monitor screen – see outside at a glance, weather info
It might be possible to create an alarm/temperature combo sensor to deploy in multiple rooms using Atmel+Wifi, to feed alarm and temperature and allow remote display and control ability.
Get Octoprint via Octopi working with Anet A8 printer
Get Anet A8 printer working reliably
Neighborhood video security system (might require non-profit organization)
Compile own options on Linux, for Raspberry Pi
Firewall controls for wifi – limit specific devices to times and block some services – Onion Omega or commercial wifi router, perhaps updated to Openwrt.
Data server (NAS) with existing USB hard drives
Backup server (DVD writer)
Print server (Brother laser printer)
Minecraft server (for son, perhaps one for myself) Pi – with logging turned off, and some sort of automatic backup (cloud or to local PC or NAS)