Android phones, apps and tablets

i finally recieved my desire (which was a desire) so will be asking plenty of dumb questions. Firstly...
Is there any sort of agreement on the best or most useful general apps? And more importantly, what's the best music player? All my stuff is on itunes so maybe that doubletwist one flagged a few posts back? anyone used it?

B.

Doubletwist is great, I'd recommend it. Best thing about it is that you can sync wirelessly with your pc/mac as well through itunes.