Hi.... I've been sharing an iPad belongs to my wife & I came across a unique PDF Reader i.e GoodReader. This app is an excellent editor to PDF file in the sense that you can use sticky notes, lines, arrows, and freehand drawings on top of the PDF file. Pls check: GoodReader I will soon migrate to Adam tablet and since my line of work require me to edit architectural drawings on the go at project sites, this is an excellent choice of apps. I've been searching for an android app equivalent to this. Hope the guys here could help me out. Regards.