I suggest trying Notability. It allows you to sync & amplify audio with notes so you always know what you were writing during a given point in the lecture. Notability also allows you to insert pictures, we images, and hand written notes and drawings. While writing you are also able to customize text with size, font, bold, colors, bullets, numbering, etc. The notes can easily be filed and labeled so they are easy to find. Notability also supports exporting the notes as a pdf+recording or simply a pdf through drop box. Coming soon it will support iDISK and webDAV as well.