Acorn is an online streaming video service that curates some of Britain's top television shows and offers subscriptions for viewing this content on demand, commercial free. Acorn's subscription prices are amazingly low, and you can subscribe for a year or a month (with a 3-month minimum required). The cost: $29.99/year or $2.99/month.
Subscribers gain instant access to the television shows upon signing up. They can view Acorn's selection of top British mysteries, dramas, etc., anytime they wish, 24/7--and can watch any program repeatedly (i.e., they're not limited to a one-time viewing). Please note, however, that Acorn does not offer top current programming--such as famed Downton Abbey or DCI Banks. But most of the top "oldies" are available. Also, the service is currently available only in the US and Canada--though it may expand to other countries in the future.
Acorn TV is accessible on computers, iPhones, iPads, Apple TV, Google TV, and Roku (a device that allows the media content to play on your television set). The service offers over 125 hours of programming at any one time, including full seasons of 18 different shows--and new titles rotating into the schedule each week.
Acorn also sells DVDs of their programming, and if I have any complaint at all about the service, it's that they give quite a bit of space on their site to the selling of these DVDs. On the other hand, it's easy enough to ignore this content if one has no interest in it and wishes to only watch streaming video online.