Earlier, when I posted about Dropbox, I missed the apps with Dropbox integration. These apps allow the user to sync their information with Dropbox from within a specific mobile or web application.
One app of note is Aron Nelson’s unrealBook for the iPad. It is a PDF music viewer imports your PDF’s of music via Dropbox. There are several apps that allow you to view your PDF music collection, but the process of getting your music on to the iPad is much less user friendly. unrealBook also allows the user to make annotations or notes in the music. This is a big advantage over some of the other music viewers.
unrealBook is $4.99 and is available through Apple’s App Store.