I always loved the simplicity and form-factor of the Model 100. For a "practical" modern version, the tricky bit is getting data on and off. Wifi/ethernet would definitely replace the modem, but for comms ssh/scp isn't that convenient for folks looking for something "simple". Personally, some combination of Dropbox-esque file sharing and SMB disk mounting strike me as practical.

I doubt that there's anything like a commercial product here, but I find it a really fascinating design space.