In the past we have seen unlimited mobile broadband contracts that can end up with users being charged per MegaByte if they go over a fair usage level of perhaps 1GB in a month. Three in a drive to attract customers has removed this fear of unusually high bills, by committing to not charging for out of bundle usage.
Contracts are available with a 250MB bundle from £15 a month, which if you hit the limit can be topped up at a rate of 250MB for £2 or all you can eat that month for £5. Monthly contracts with an all you can eat data allowance start at £18 a month.
There is a big caveat before everyone gets a cheap Three mobile to act as a dongle for their laptop, and that is that tethering is not allowed on the all you can eat data plan, an add-on is required that will provide 1GB of data for use with a tethered connection.