Notability

– Notability description and YouTube demo by vendor, Ginger Labs
– Notability description in Apple’s App Store

Reviews:
– How to upload a PDF from Notability into Dropbox, YouTube demo by ephansonss
– Notability – unleash Your iPad…, Trevor Sheridan, applenapps.com, Dec 3 2012
– Notability – Take Notes & Annotate PDFs…, Jason Parker, cnet.com, May 23 2011
– Notability for iPad, Joel Mathis, MacWorld.com,  Dec 12 2011