I'm not usually one to hype these sorts of things but this truly is an amazing piece of FREE software and a must for anyone with a Sony PS3 hooked up to a home network.
It is essentially a one click button that allows your PS3 to access all the media on your computer (I think a PC version is available but I've only tried the Mac).
I admit the only thing it adds is convenience given you can easily use a USB drive to act as the drug mule. However, for people like me with thousands of photos, songs and video files, this app really allows the lazy bastard to sit and play - browsing through thousands of files on the TV.
On top of that, if you have a external HD tethered to your router e.g. Apple Time Capsule (or for tightasses like me, an Apple Airport Extreme with a HD drive), you can access all of your media files from that device too.
So what's the end game? I can store all of my media on one drive (connected to my router) and access all of it from my desktop, laptop and TV.