I commute several days a week via Caltrain to Palo Alto, so I like to work during my commute. Unfortunately Caltrain doesn’t have Wi-fi and I easily go over my data limit when tethering my iPhone, so I found a much better solution: Karma Wi-fi.
Karma provides a portable 4G hotspot like many others, but what sets them apart is their business model: Every time someone connects to your hotspot, you earn free data. Their basic contract-free plan gives you 1GB of data for $14, but every time someone connects you earn 100MB of data. Since I’ve had mine, I’ve earned 1.66GB of data.
The coverage is good in San Francisco & Palo Alto, but unfortunately there are a couple of dead spots along the way, most notably around Bayview & San Mateo. Outside of those spots, the 4G speed is excellent.