I've never counted, so here we go. Between my wife and I:

3 macbooks

1 chromebook

3 smartphones

1 roku

1 XB1

1 NAS

1 DirecTV box

1 IP printer

1 smartwatch

1 iPad

1 Sphero

2 Chromecast

So in total, 17. That's being a bit liberal with the Sphero and chromecasts, since they don't actually have internet access.