One nice thing about Banshee was the seemless integration of the Amazon MP3 store. Since I reinstalled my laptop on Precise, I know have Rhythmbox instead of Banshee which does not seems to offer the same kind of integration.
Luckily for me, I found a nice little hack that will help me get my favorite non-DRMed MP3 files on Ubuntu :
http://ubuntuforums.org/showthread.php?t=1955149
In short, install clamz that will allow you to read & download the .amz files that the Amazon music store sends when you buy music.
Hope this helps