The first app, I helped out in the production of. It was put together for the recently released (and first for a very long time) new album from Gavin Friday, catholic
The second one was brought to my attention via the ever excellent ModCulture website, and is called The 45 Fix (info here). Currently only available (or useful) for UK record nuts, its basically an record store app. According to ModCulture, many second hand shops are currently not listed, but that will change over time. I hope the developers of this one can get it together for the States. What an amazingly useful idea!
Lastly, we have turntable.fm, proving that many times the best ideas are obvious & simple. Turntable.fm combines two old ideas into one new, and quite fun one - playing music with friends & chatting about it. Basically, there are virtual rooms which are user created. Each room can have up to 5 DJ's, along with unlimited listeners, and each DJ takes a turn playing a song. And everyone can chat...it's quite addictive, and a great way to listen to music...I'm sure the RIAA & music publishers will find some way to fuck these folks over, but I hope not. Anyway, have a go while you can. Its a blast!