I've accumulated quite a collection of videos over the years and my game systems (360 and PS3) have long been a way to watch them someplace other than my PC. I know, 360 and XP Media Center are *supposed* to stream... I'd rather go to the dentist.
In the past I used to have to burn anything I wanted to watch to a DVD, as it was the only supported format. This could be a time-consuming process and if it was something from the web, there were sometimes compatibility issues with my DVD burning software. With the introduction of native support for several media formats I now had the ability to copy files to a USB drive and play it on my PS3. I did try several times to connect my USB HDD to my 360 but it just rekindled the desire for dental surgery...
Today I was having some issues with a large AVI performing poorly from the external drive so I decided to Google "USB Video Performance PS3" and very near the top of the list was a Gizmodo article from last November. Most of the article was old news to me, as I'd been using external media to play videos for years but it did reference and app called TVersity.
TVersity comes in two flavors, Free and Pro. The Free version will give you everything but the ability to stream web content (Hulu, YouTube, Sling) but you don't have to pay up front for Pro and the web content is cool. 
The setup is really simple and the interface sharp and reasonably intuitive. In less than 10 minutes from downloading the app I was watching streaming content on my 360, directly from my PC. My old issues of potential codec/format compatibility is gone now, too. TVersity has a client-side transcoder that will decode the stream on the fly.
While some of my friends are gleefully harassing me for *just* stumbling on to this, I see it as the dawn of a new era in my home entertainment. Well, off to configure sling.com..