#84 Optus Maximus
Optus (an Australian phone service provider) used to have a prepaid, unlimited credit cap for $3 a day. So, I signed up for the cap, put the sim card in a spare phone and used it as a Wi-Fi hotspot, making occasional phone calls and texts to my regular mobile just to make it look like I was using it for a phone.
I was essentially getting unlimited data for $90 a month. At my peak, I was downloading 20 GB a day. I kept it for 3 years before Optus clued into what I was doing.
Credit: esskay1711