you can always screen cap a map (home button + sleep button) at whatever zoomed level and THEN draw your directions to the secret treasure or what have you!
I prefer ZeptoPad. It makes adding text possible, rather than just scribbles, and it has unlimited canvas size available. It's a bit more complex but just as powerful.
ZeptoPad doesn't properly import photos from the Photo Library. Instead of importing the photo, it imports only a tiny thumbnail--and this thumbnail can NOT be scaled up without dreadful pixelation.