Karma's device costs $79 and offers a reasonably-priced pay-as-you-go 4G data connection with no subscription or contract.
Click here to go hands-on with Karma >
Furthermore, your hotspot remains open for other people to connect to if they want. Every time a new individual shares your connection, you get 100 MB of free data and they get 100 MB of their own data.
At no point will a stranger's data usage affect your own. You're simply sharing a connection, not the data allowance. Additionally their connection will be throttled to ensure that you, as owner of the hotspot, don't even see a loss of bandwidth.
To prevent people from gaming this system, people are required to log in with their Facebook accounts before being able to use a Karma hotspot.
You can top off your data at a flat rate of $14 per GB.
We've been using it lately and have been really pleased at how painless it was to set up and how speedy and reliable the connection is.
If you're intrigued, then check out Karma's coverage map here.
Until then...