The Karma is a very small revolution in tech: it's a gadget with a data plan that makes sense, is transparent, and doesn't try to screw you. This should not be a crazy great thing. And yet it is.
Portable Wi-Fi hotspots are, for the most part, great to use and awful to pay for. They're tiny little devices that gives you fast internet access no matter where you are, by tapping into the same fast networks used by Verizon, AT&T, Sprint, and T-Mobile. Until all our laptops have little SIM-card slots in them, this is the best way to get online in places without a Wi-Fi connection. Great! Except it costs an arm and a leg, and requires a contract, and forces you to ration yourself every tiny little megabyte. So, yeah, Wi-Fi hotspots are trying to screw you.
Karma isn't the most high-tech hotspot out there, but unless somebody else is footing the bill, it's the one I'd recommend, because not only is it not trying to screw you, it actually rewards you for un-screwing (AKA helping) other people. That help?