A small, battery-powered wireless router that runs on 4G. It broadcasts a configurable SSID which defaults to "Starbucks Customer Wi-Fi", and prompts users to

A small, battery-powered wireless router that runs on 4G. It broadcasts a configurable SSID which defaults to "Starbucks Customer Wi-Fi", and prompts users to "download secure browsing certificate", which actually downloads a (known-to-the-router) SSL cert, allowing for MitM attacks against users browsing HTTPS websites in coffee-shops. In case actually snooping the web traffic and exploiting it is too much work, the router can also replace all ads and e-commerce links with those that would pay the owner of the router. Finally, in a surprise twist, a small percentage of all injected ads and affiliate links actually benefit the company selling the routers, rather than the owner. EDIT: I think I know what I'm doing this weekend.