Asst the risk of sounding stupid, what is it?
The short version, it's an iPhone app that takes everything on their website and makes it "easier" to use on a small phone.
Discogs is a website that taps into a huge online database of almost everything ever released. You can research artists or releases, buy or sell, create your own catalog, create wantlists and the list goes on.
My wife doesn't know what we have, so I'm trying to catalog everything. She'll be able to go to my collection on the website and pick what she wants to listen to. Or if she's out in a record store she won't bring me home 7 records I already own.