Playon is a commercial server that aggregates content from web sites using ‘official’ and ‘unofficial’ plugins and scripts. A free version streams your media. See the full list of channels here. Playon channels are, for the most part, aggregators of files posted to internet servers. The Food Network, for instance, is a bunch of episodes or programs that are on the Food Network rather than a continuous stream of programming.
Playon supports a wide variety of devices including all three game consoles, iStuff, and the Roku. See the complete list of supported devices here.
Playon is relatively inexpensive. For $70, you can purchase a lifetime subscription that comes with a Roku LT. Since the LT is $50, you are getting Playon for life for $20. I took that chance and recommend you do the same. Unlike TIVO, the Playon license does not expire when your hardware fails — you can transfer your license from machine to machine forever. The only limitation is that the license is for the current version of Playon. The current version will not stop working when a new version is releases, but you will not get a free upgrade to the next version. It’s not as limiting as it sounds, you only need to upgrade when Playon adds functionality or channels that you’re willing to pay for and Playon offers discounts to upgraders.
One of the things I like about Playon is that I can use it to watch TV on my Kindle Fire. To do this, simply open the silk browser, disable accelerated browsing (tap the menu button, tap Settings, toggle Accelerate Page Loading to off), then browse to http://m.playon.tv.