I just downloaded StreamToMe to my iPad to let me automatically transcode and stream videos from our video server (a mac mini) directly to the iPad - and it works (most of the time - unless it crashes).

It requires that you run a (free) application on the server - then the iPad will automatically discover all servers.

StreamToMe is an application for iPhone and iPod Touch that plays music and video files (in a wide variety of formats) streamed live from your Mac. If you connect the video-out cable for iPhone/iPod, StreamToMe can play through your TV, turning your iPhone/iPod plus Mac into a home media center.

[From Projects With Love: StreamToMe]