We have talked about Plex here on TDL a few times, with clients for Mac,Windows, Android and iOS devices. The latest client launched is Plex for Roku, at the moment the beta only supports video but Plex plan to add music an picture support.
The Roku client is considered beta, and supports only video content at the moment, although photo and music support will be added in the future (what can we say, we were super excited to share it with you!). The devices have great video playback capability, and they support Direct Streaming, which means high quality video without transcoding in many cases. Give the new client a try, and let us know what you think in the new Roku forum!
More details from Plex