Missing Remote takes a look at software based media streaming solutions. They specifically highlight Orb MyCasting, SageTV Media Center and WebGuide 4.

Quote from the Guide:
"Videos are probably my personal favorites here, as I would use this more than anything while I travel. Sure I load up my laptop with videos, but there are always times when I forget or just feel like a different one I know I have at my home. Now, of course, you're giving up quite a bit of quality to do this (based on your internet speed), but better than nothing. Again, not much different to say in terms of usability/experience compared to the Pictures, which is a good thing. It's not hard figuring out how to play a file or navigate through your folders.
Read the full streamer guide on Missing Remote.