This is a simple test to limit the number of logins a single user account can make.
Each time a login happens we stamp that resume token according to the device type as detected by bowser from the user-agent string, and we revoke all other tokens for that user with the same device type.
Meteor reactively watches the login tokens and automatically logs out any session which loses it's token.
Install Meteor, check out this repo then npm install && npm start
This uses the private Accounts._getLoginToken method, which could presumably change in the future.